For online (social oriented) community building Toolset can be a part of the solution but not the solution per se.
Toolset offers "only" 3 types of forms, being those User Forms (to create and edit users), Post Forms (to create and edit any kind of posts) and then relationship forms, used to connect Posts.
It features no chat, online status, friendship or other forms of connections, "wall" (like facebooks) or other social-oriented features.
For that, BuddyPress and WP Symposium (PRO) are probably the most common, and reliable solutions.
Note, none of the 2 are integrated with Toolset, means especially for BuddyPress you cannot design their templates with Toolset.
WP Symposium (PRO) is a bit easier on this as it works a lot with ShortCodes and does not necessarily force templates.
Hence, in relation to your requirements, it depends a lot what you understand under "Online community"
This can be an advanced chat and wall system with interactions, or a simple blog.
Depending on your requirements some things can be done with just Toolset. Others would then need add-on software.
"Online forum" falls kind of in the same area. While it is absolutely possible to create let's say a Post Form. where users submit posts (forum posts) and even other users could answer to them (using a Post Relationship where the answer is a child post to the parent question), it is relatively fast out of options, since you will spend a lot of time if you also want things like "upvotes", "likes", several answers and sub-answers, etc.
While it is possible, it's not what Toolset was directly made for and other software is coming ready for it out of the box.
It really depends how far you want to go.
For example, I managed to create (and could explain how) a Forum, with just Toolset, where an user asks a question, and other users can:
- "me too" this question (thumbs up)
- answer the question
- comment on the question or answers 3 levels deep
- mark the question as solved
- get email notifications when any of their questions or answers is either answered or commented.
But the amount of work for this, inclusive styling, compared to the fact that in BuddyPress or WP Symposium (PRO) you set this up with the click of a button, is not really justifying doing it with Toolset.
"Membership capabilities/levels" should be something where Toolset can already help much more.
We have Toolset Access which lets you set up user roles, permissions, control who can do what, and soon (next release) also support several roles each user.
This can help a lot to control who can see what, do what and when, both in the backend and front end of WordPress
It does not allow you to set up recurring membership plans as you know it from paid membership sites.
For that, a mix of Toolset and at the best case a membership plugin should do the trick
"The ability for certain membership levels to create their own website (WP Multisite). The main community would reside at the main/parent site. (something like this hidden link)" and "Some Member levels could have access to other sites on the Network (similar to this hidden link)"
This is unfortunately not possible with any plugin I know, mainly because cross-site administration of content and users is not possible in WordPress itself.
Yes, you can share the users, but you cannot easily share their content.
Toolset itself does not allow site-crossing control or network/subsite related control managed from one point.
You would have to set up each site as a standalone site.
I have been at that point as well, I finally renounced to Multisite and just used Access to hide/show certain aspects of one, bigger site.
But, I did not need users to create totally new websites on my network.
"Fitness Log or Journal - Certain membership levels will have access to their own fitness log/journal. They can make it public or keep it private." and "Certain Members will be able to create their own content to share with the community. This will include written, photos, video, and potentially audio content (maybe others)." and "Certain members will have the ability to add photos to a photo gallery."
This should be possible with Access and Types and Forms.
Of course, it will be a bit tricky to allow those users to choose whether their content should be public or not but nothing unachievable with Toolset.
Here you will not need any add-on software.
"Member directory"
If you mean a list (searchable) of members, this can be done with Toolset Views relatively easy. No add-ons are needed here.
"The main site will have a shop using Woocommerce"
This is totally up to you, it is not really related to Toolset.
However, I want to let you know that you can style the shop and products with Toolset (even create forms, where to submit it the user will have to purchase a product)
Hence, you might gain from Toolset a lot on this area of the site.
"Integration with Mailchimp or ConvertKit (do you have a recommendation for either?)"
Toolset does not integrate any of both, usually, we offer Toolset Forms to send out notifications (for example once a form is submitted, a post published, an user created).
But, it also does not knowingly conflict with any of those plugins, hence if you need them, you should be fine while using Toolset along.
"Affiliate program to incent members to promote the community"
This totally depends on what precisely this would be.
I mean, you could motivate your users to share a link for example, but Toolset doesn't offer any methods to add "perks" or "incentives" to a personal link.
For this, other plugins would need to be used or some custom HTML/PHP eventually.
Of course, Toolset will help you greatly in creating the needed templates to display all that, and eventually even storing the data gathered.
"All content entry from Members/Users should be on the frontend. This includes managing their account as well as submitting content to the main site."
This definitely is something where Toolset Forms and Views can help greatly.
You can have (almost) all WordPress on the front end by creating the right forms for it (user, posts or relations)
In Views, you can create lists, and hence, for example, list a lot of links to single forms as a "user directory edit admin page" or similar.
Your project will likely require some other software especially to handle the membership and forum aspects.
With Toolset, you can create and manage the Custom Content (posts, taxonomies, fields) and eventually the users.
Great also it'll be to list your content easily on the front end using Views, and allowing/denying access to particular parts with Toolset Access.
Finally, you will enjoy the most (I think) the design part with Gutenberg Blocks on Content Templates, allowing you to apply the same layouts to hundreds of pages, posts or user archives at once.
For specific questions (single doubts, hurdles etc) please open up one particular ticket each question.
Then, a supporter will assist you in that topic, each time one topic each ticket.
We can help with almost anything, even some custom code samples, as described here:
https://toolset.com/toolset-support-policy/
This site is gathering a lot of such samples already: hidden link
These threads might also help you decide further:
https://toolset.com/forums/topic/create-facebook-like-friends-relationship-for-a-post-type/
https://toolset.com/forums/topic/planning-to-do-a-multi-site-marketplace-facility-business-directory-website/
https://toolset.com/forums/topic/toolset-multisite-support/
Thanks!