Search on youtube for Winchester 1300 assembly, they are internally the same.
I recommend the Gun Digest series of books on firearms assembly and disassembly. Amazon, among others, sells the individual books (Part V deals with shotguns).
This requires the services of a gunsmith.
You need to take it to a competent gunmsith
yes they are one in the same
Yes, but ejector spring may need modification- slight change in slot for spring.
If you removed the bolt, you probably lost the ejector spring. A new one can be had from Numrich Gun Parts. To replace the ejector spring, remove the bolt, and take out the spring from the bottom of the receiver just behind the ejector port.
no. the bolt is push feed with a button ejector and plate extractor vs. a standing blade ejector and mauser style claw extractor in the pre 64's.
You should be able to find a assembly-disassembly guide for your Winchester model 37 on E-bay.If not you may to need to visit a qualified gunsmith.
Brownells gunsmithing should have a wrench that fits your Winchester model 12 end nut. this site is available on the web.
Best left to a trained gunsmith.
Ejector will depend on barrel elngth (short barrelled revolvers have a short ejector rod as well) Check Numrich thru their website at gunpartscorp. You can also check Brownells, or any competent pistolsmith. When all else fails, check with S&W for recommendations.