If I laminate the A4 sheet that they are on and then cut the cards out will the laminate still stay on the cards or just peel away. I know you can buy credit card size laminating pouches, but if i buy these will they work on a laminator that accepts A4 pouches? I dont own a laminator yet and dont want to buy one if this idea wont work

Yes- most require the paper pouch… read the instructions that came with the laminator. It will tell you if you need one for sure or not. If it says to use one then you should- otherwise you could ruin everything.

I own a Purple Cows laminator. Do I have to use the Purple Cows brand laminating pouches with this laminator or am I able to switch brands? I’ve noticed that the P.C. laminating pouches are slightly more expensive than, say, Scotch brand and I wouldn’t mind switching as long as it doesn’t harm my laminator.