First of all, what works best for you to use in your container to make the dipped mandrels stand up?
I grabbed an old chunk of wood and drilled holes in. Worked so well I made two more.
I saw one person uses sand which sounds messy
It was messy for me I hated using sand.
and beans are kind of high for a large container. I don't really like the look of the mandrel stands.
Anything that is pretty and made out of wood you could drill so it could be an artsy item in itself that would be uniquely yours. Driftwood would be pretty. You could buy a large cookie tin ( eat all of the cookies first 
) then fill it with marbles or? drill or hammer holes in the top and viola' a dipped mandrel holder. 
.
http://www.amazon.com/Danish-Butter-...rge+cookie+tin
Next, when you buy a propane tank, what size?
Normal 7 gal BBQ tank. But I also have a smaller 3 gal.
If you buy the smaller size that is used for gas grills, do you go to the convenient store and trade for a refill or go to a gas company and get your tank refilled.
Neither. I take both sizes to one of the local RV parks. They fill these things all of the time and have it down pat! The people at the stores scare the heck outta me
I would think that when you buy a new one, you would always want to use your own tank.
Correct. I know what fuel has been in it and it is very clean.
I know...I shouldn't sound like such a beginner, I'm just getting my studio ready. I can't wait to post pictures!
Please offer your opinions.
Tippy
It is so exciting to get it all up and running! Have fun, be safe.