Anyone ever been a recruiter

There are a couple ways you could go about it.

1. Freelance on an hourly basis: either work directly with a company helping them fill open roles or work for a recruitment agency on a set hourly rate.
2. Fee-based recruitment: this is how recruitment agencies operate and charge a % of the hired candidate's salary. It's an extremely competitive market, so may be difficult to find companies willing to partner.

If you do want to go with #2, you will want to execute a contingency agreement with the companies, which essentially outlines what they will owe you if/when they hire a candidate you identified. (Standard language will also include a 'guarantee' if the candidate doesn't work out - this can be a full / partial refund or simply a replacement candidate at no additional cost.)
While this option is more lucrative (standard fee is 20% of first year salary in the US market), it will take significantly longer to start earning. Figure a typical search takes 60-90 days to fill + 30 days after the candidate starts to get paid.

I would recommend going the freelance route to start. It will be easier to land a paying gig sooner and is the best way to learn more about the field and how to navigate managing an end-to-end recruitment process.

Don't have to the answers to your questions...

But the gig idea is good. I'd like to know where you find those part-time recruiting gigs.