Answering your direct questions first:

.... or posting links to GitHub instead of code chunks, etc.?

The keyword you use here is 'instead', and the answer is 'no'. You cannot post questions here with links INSTEAD of the code. You can post questions with both the code, and the link though, if you want. Only the code you post in the question is for review though, the rest of the linked code is for 'context', or convenience.

There are lots of ways to post working chunks of code from larger projects here on Code Review, but, to be valid on Code Review, the question has to be self-sufficient. See: including code.

If you post interesting questions with good code, then you may well find others showing interest in the project as a whole.

As a a side note: the flourishing of a couple of projects is a good thing. Parts of Code Review have a community feel to it. There's a bunch of smart, interesting folk who swing through, and some of them are even regulars. These projects that have arisen are more a function of the fact that if you put like-minded people together who get an idea, then something will happen. These projects are not 'promoted', or 'driven' by Code Review, but Code Review happens to be a place where people actually communicate, and share, and work together. People who were, essentially, 'friends' got together, and worked on something. In both instances, the idea, motivation, and continuation of the projects have happened primarily in chat, rather than the main site. Still, as people have worked on code they have posted interesting parts to Code Review as questions, because we all like that, and we all like rep ;-)

Similar things could happen with your project.

I am not sure how you could actively recruit people while staying within the 'rules', but, for example, I maintain the JDOM open source project, and I drop the name as often as I can ;-). As a moderator, and active user, I end up communicating that fact quite often. It's in my profile, etc. That's all part-and-parcel of 'networking' in what amounts to being an online community.

Answering your direct questions first:

.... or posting links to GitHub instead of code chunks, etc.?

The keyword you use here is 'instead', and the answer is 'no'. You cannot post questions here with links INSTEAD of the code. You can post questions with both the code, and the link though, if you want. Only the code you post in the question is for review though, the rest of the linked code is for 'context', or convenience.

There are lots of ways to post working chunks of code from larger projects here on Code Review, but, to be valid on Code Review, the question has to be self-sufficient. See: including code.

If you post interesting questions with good code, then you may well find others showing interest in the project as a whole.

As a a side note: the flourishing of a couple of projects is a good thing. Parts of Code Review have a community feel to it. There's a bunch of smart, interesting folk who swing through, and some of them are even regulars. These projects that have arisen are more a function of the fact that if you put like-minded people together who get an idea, then something will happen. These projects are not 'promoted', or 'driven' by Code Review, but Code Review happens to be a place where people actually communicate, and share, and work together. People who were, essentially, 'friends' got together, and worked on something. In both instances, the idea, motivation, and continuation of the projects have happened primarily in chat, rather than the main site. Still, as people have worked on code they have posted interesting parts to Code Review as questions, because we all like that, and we all like rep ;-)

Similar things could happen with your project.

I am not sure how you could actively recruit people while staying within the 'rules', but, for example, I maintain the JDOM open source project, and I drop the name as often as I can ;-). As a moderator, and active user, I end up communicating that fact quite often. It's in my profile, etc. That's all part-and-parcel of 'networking' in what amounts to being an online community.