In order:
As I recall, the .30 Carbine is "about" comparable to the .357 Magnum.
You can hunt small game, and small deer with the Carbine. Most any smaller animals can be taken with the Carbine IF you use sporting ammo, and stay within the Carbines range.
The Carbine, again loaded with sporting expanding ammo is an excellent home defense rifle. It's small, light, short, very "handy", has a large magazine, GI versions in good condition and well maintained are very reliable, and at short home defense ranges it does the job.
You could easily do worse.
The Carbines effective range is "about" 150 yards and under.
Overall, the Carbine is a finely made rifle, with an excellent reputation. When it was used in Korea at longer ranges it got bad reports for failure to stop.
Noticeably, in WWII and Vietnam when used at the shorter ranges it was designed for, it got a good reputation, especially among the actual combat vets who used it.
Among others, Audie Murphy very much liked the Carbine.
Concerns:
Try to buy a USGI Carbine in good condition. GI Carbines are at least 60 years old, and may be worn or abused.
Modern commercial Carbines are often not made to USGI standards and may give problems.
The usual cause of GI Carbine problems are old or commercial magazines, and ammo that's not made to strict GI standards and specs.
Buy good magazines, preferably USGI, and note that MOST 30 round magazines are either worn out GI or substandard commercial copies.
These 30 round mags often give problems, so you may be better off to use USGI 15 round mags.
When you get a Carbine have it checked out or check it out thoroughly.
Suspect springs should be replaced with USGI springs ONLY..... NO "extra power" springs. The Carbine was designed to work with GI spec springs and stronger ones often cause problems where there were no problems.
CLEAN the Carbine and if the gas piston seems sticky, have a qualified gunsmith disassemble it and clean the gas system.
If it's necessary to disassemble the gas system, replace the piston and piston nut with new GI parts.
Keep the gas system DRY. NEVER allow solvent or lube to get into the system.
Any thing allowed into the gas system will be burned to a tar-like substance by the super-heated gas and will cause stoppages.
When used with GI-spec ammo, the gas system was self-cleaning.
If you need to dissemble the gas system or bolt, use GI-type ordnance tools.
There are GI and commercial copies of the GI gas piston nut wrench and the bolt disassembly tool.
It's not unusual for GI carbines to have worn, fouled, or weak extractor and ejector assemblies. The bolt tool will allow the bolt to be easily disassembled for cleaning or parts replacement. While you "can" disassemble and reassemble the bolt without the tool, you'll WISH you hadn't.
Lube the Carbine properly, preferably using a good grease to grease key parts like the bolt, op rod, and receiver. Where ever you see wear taking place.
If the Carbine has operating problems, try different ammo, and different magazines.
