I have a question, when you get a buy one get one free item at Publix if you had two coupons (one for each item) could you use them both or not because technically you are only purchasing one of those items?
That is a YMMV situation. There is a snotty manager at the Publix at Town Center who claims you can't use two coupons since you're only paying for one, but she's the only one I've ever had a problem with.

Also, at CVS if you were to buy several things in one transaction that had the extra bucks attached to them do they add them up or should you make separate purchases for all the items?
If you are buying multiples of the same item they will print on one ECB...but if you are buying different items they will print on separate ECBs

Last question, with that $4 off cosmetic coupon you posted, does it just have to be one item or can you get a few to add up to $20?
It's just $4 off a $20 purchase of beauty stuff. If that means you buy 20 products that cost $1 each you still get $4 off.