Back when I first found this site, Token explained to me that Vermiculite helps retain moisture in potting mix while Perlite lets water/liquid drain through it. I thought I kept the email but evidently I deleted it. Maybe do a search of this website and see what pops up. I'm sure the question has been asked at some point. I recall making a mental note (scary) to use Perlite if/when I mixed my own seed starting mix since drainage is so important with the WS method.

I have added the fine vermiculite to cover sown seeds but didn't find that it made any difference so now I skip it. Sow, press seeds to make soil contact, mist, and out they go.

Mine is too coarse, used some early on but no more. If I feel I must cover a little, I sprinkle dry seed starting mix and spritz it like I read here somewhere.

The ones I didn't cover, I noticed they get washed around, some are too close together.

I don't have enough experience yet to know for sure the effect vermiculite has, think it might keep the soil too wet, and I don't put any water retention stuff in mine. When it gets warmer, they seem more likely to mold, from what little I've done.

Unless I learn differently, if you don't have any seed starter and feel you should cover, use a little potting soil instead. I usually just pat some smaller seeds in, but the bigger ones I do cover a bit when there aren't any sowing instructions. A lot of the seeds probably wash to the top anyway.

Nope. I keep things as simple as possible. I started by using MG potting mix and it worked like a charm, so that's what I stick to. Why fix what is not broke?