That's right, no taxes are taken out being that you are an IC, not an employee--you are responsible for paying income tax on your wages.
I myself just reconcile every thing at the end of the year, last year I didn't make enough for it to make much of an impact taxes, wise. I claimed all the warmers I bought, claiming them as "display" models, which they are when I take them to shows. It was pretty easy because all of your orders are stored in your workstation and at the end of the year, I just printed out all my personal order reciepts and entered everything into a ledger. It would be even easier if you did Quickbooks or something similar. Of course, you could also enter in each order into a ledger system as you go along but I am a procrastinator so it works better for me to do it at the end of the year. ;-)
There is no EIN, it just goes under your SSN.
I do use the Visa card method of wages. Like what you have in mind, I like keeping my "Scentsy money" separate from the rest of my income. And YES, you can use it to buy more Scentsy, or make purchases in the family store (Scentsy's bussiness supply store). I do that quite a lot, so it's kind of like getting my personal Scentsy for free. :-) I also use it to fund my LOTRO addiction, and other 'frivolous' purchases to 'spoil' myself. I don't really focus a lot on selling the stuff, but it's nice to have that occasional extra money to use for 'fun'. Though there are tons of consultants who take their Scentsy business as a serious business and aren't casual about it like I am and they make a TON of money--enough to live off of as their only job! I, personally like to keep it low key and just have fun with it. It's really a very flexible business.