"While I'm still very new to this trade (about 3 months in, never worked with or for anyone before) "
you need to go work for someone. learn the skills, learn how to take orders so you in turn, know how to give them to your crew. you need to screw up a handful of times so that you know how to fix them. you need to know how long it should take to do a room just by walking into it, and the only way you can know that is by doing a thousand like it before.
you need to bid jobs a little too low to know how much NOT to bid so you don't starve, and you need to bid some a little too high to know how much the customer is willing to pay.
end point is...you just need more experience. your questions aren't dumb for a beginner at all. for someone who's trying to run their own business, they are elementary.
you might be a skilled painter with your 3 months of experience *no sarcasm sign being hung* but there is a lot more to running a business than just the trade itself.
i really suggest you take your skills to a local company that is established and have them start you off at a wage an actual starting wage a painter should make of like $15/hr, and see how you fare. your skills and knowledge might not be as up to par as you might have thought, and you might get a few of the old salty men poking fun at you daily, but if you keep it up for a few years you'll walk out with skills that will enable you to run your own business correctly, and prosper.
