The card stock is just letter size...8 1/2 X 11. So, yeah, they're roughly 4x5 once cut. I just buy the 'treat' bags that are on the aisle with the Wilton stuff at Hobby Lobby or Michael's...the ones that have gusseted sides (pleated, sort of)...not Wilton's brand, as they're a little pricey, IMO, but I don't remember the brand on them...they're like $2 or $3 for 50 bags. I think I've used Wilton's cookie bags before, too. The tag ends up being just a little bit wider than the bag itself, but I kind of like the way it looks. You could cut them down, if you like, to the exact width of your bag...but in my mind, that would just take soooo much longer to do. And the difference in width, of the tag and the bag, is so little really.
As for flipping the business info upside down...well - I guess it depends on what kind of program you're using.
I have Microsoft Picture It! that's pretty much just for making cards, photo projects, pretty simple stuff. My business logo/info is a separate project on it's own...so I cut and paste it into the 'cookie tag' project, when I'm making them. Then I can move it all around by itself, shrink or enlarge it (while keeping it in scale) depending on what I'm working on, without changing anything else in that project....it has a box around it and I just select it and then choose to rotate it until I have it upside down. Then I can 'grab' it and position it to where it's centered over the image/text that will be the 'front' of the tag. Gosh...I'm sure I'm just explaining this horribly and confusing you!
Lemme know if you have any more questions...maybe my brain will be working better later & I can make some sense!!