If you have enough money, you can have one made.
Tripple K Magazines make 15 round mag's for the Raven,the older Phoenix ,and the beretta.I know where to get a berreta and phoenix now.
25-65 USD
Small handgun
small .22 or .25 caliber handgun
S&W never made a 25 ACP handgun for retail sale.
No published sn data.
50-200 or so
Magazine, not clip, and it varies dependent on which handgun you had in mind, specifically. For most .25 pistols, six or seven rounds is the norm.
AFAIK, none. There were one or two importers in FL that sold 25 ACP pistols.
As long as it's the correct caliber, yes.
10-1000 USD depending on specifics
The short answer is no. The longer answer is, you may be able to get a .25 cartridge into a .22 caliber gun, but it will likely jam and be very difficult to get out, and if it fires, it will probably damage the gun and possible the shooter. The .25 has a larger diameter than the .22.
$25 or so. Low value handgun.