they have a detailed description on their website.
for belts, bends are the best.
you won't get anything of grade A/standard (the best) grade. Even their B grade often far from B/second
who would buy this tool for 80 bucks??
i'm using one from SLC and it does the job for 27$ - https://www.springfieldleather.com/Strap-Cutter-All-Purpose
sometimes it's not a sellers job to tell why and how - recommendations and personal touch will put the dots in place.
some buyers rely on a feedback and some won't believe until use it and convince themselves that the item they have paid is worth the money.
if the edges separate from each other then you're doing something wrong.
edge paint will do the job, unless you want the edges looks good. but you have already stated 'not looking for perfection' - this confuses
you'd better start from basics as you are asking questions already answered many times.
get some leathercraft books - you will find them useful and those questions will be gone.
I barely (almost none) face customers asking for the option of changing buckles.
sewing is the strongest way to get layers hold together compared to rivets and chicago screws. Perforations has nothing to do with the weakness.
stitches also aesthetically beautiful