ill be buying a new fork and not sure what to look for in order to have it fit (new to "modern" bikes)

26 check
1 1/8 inch(or something?) headtube -check (have to saw leftover headtube off? have tools)
100-120mm travel -check
quick release -check
discs -check
hub spacing/size?? dont see it anywhere, one size fits all?
bearings?
total lenght of the fork?
different disc mounting options?
disc spacing??

on google i found: XC International Standard for 6" disk, must have the manual around so i can verify, the new fork im looking at says: Postmount 6”, max. disc Ø180 mm (im running 160?), is this a problem?

anything else?