Hi Sami! and welcome
First off, sounds like you are a little stressed, but you have come to the right place.
IMHO buying a scope for someone else is fraught with potential difficulties, as even the cheapest scopes are still quite a lot of money and good scopes can be a lot of money.
Do you have any idea what your friend is interested in using the scope for? It is always best to discuss it first before laying out the foldings!
Both the scopes you have mentioned are on the expensive side for their aperture, the Celestron is about $1500 and the Meade is about $1700 at Bintel ATM. To answer some of your queries, ACF in the Meade scopes probably isn't worth worrying about if you are purely using it for visual observing. Yes it produces a flat field but only the keenest most experienced observer could tell the difference by eye. If they are imaging it may be of some value. As far as Meade vs. Celestron, probably much of a muchness as far as optics go, really more price and features.
As far as space goes, the scopes you mention still take up a fair bit of space unless they tripods are fully disassembled each time. If space in an option consider a 6" or 8" dob. Much easier on the wallet, easy to use and store and the Skywatcher collapsible GOTO 8" is around $1100 ATM, so you get more aperture, a compact scope and Go To for less $$$!
Hope all this helps
Malcolm
