maybe a primer on them, how can a newbie like me make the right choices about which to use?

The most common choices and the pros and cons thereof. Odd choices that are surprisingly effective.

Cover crops require a fair amount of extra seed. And yes some seed is cheap, but what might a person grow that can produce lots of extra seed to use in cover cropping. I know this context/climate dependent. I like using winter rye and I do grow some to harvest seed and straw. It's a strong plant and...

can "weeds" be used as cover crops? is the STUN method applicable here? how collaborative are the plants, when does the collaboration end and fighting for resources start?

How do you figure out minimum seed density for best ROI.

Been thinking about planting clover in our raised beds along side other veggies. Hoping it would deter weeds, help with nitrogen and bring in bees but I can't find a lot of information about doing it