Hi Krystal, and welcome to SaleHoo
To answer your first question, if you have an interest in sales, then SaleHoo is most definitely for you : )
Now in regards to drop shipping, you shouldn't need any tax id to deal with drop shippers. At least I certainly am not aware of any that require you to be tax compliant. This is something you would find if you were dealing with Wholesalers.
Of course if you are operating this as a business, then you would need to make yourself compliant regardless of who you used as a supplier.
Selling at weekend markets can be an excellent avenue to exploit, however drip shipping isn't an option there as you really do need stock on hand to do any serious business.
If you had time on your hands I would be suggesting you head off to some local garage (yard) sales, as these can prove to be a gold mine for stock at rock bottom prices, even lower if you have the ability to talk a good deal
The second option I would suggest looking at is liquidation. It gives you the ability to still buy in volume, but at a dramatically reduced price. Now thats aid, bare in mind that you are dealing in surplus stock, and therefore really need to understand that market before jumping in and buying a load of worthless garbage by mistake!
Lots of avenues you can look at here, and I like the way you are looking at a weekend market avenue straight away, as most will only consider online and that of course limits their market straight away!