1. You should be ok with 50amps at 100'.
2. Since the trailer is already hooked up, it's safe to assume the receptacle is correct.
3. 100' will weigh a bunch but I would assume you're not going to be lugging it around much.
4. Depending on your situation and how long you'll be using the cord, I'd protect it by slicing a few pieces of 1 1/4 pvc for it to lay on to protect it from rodents and gravel etc.
5. When you're finished with it, you can always cut it up into smaller pieces which are more manageable. My cord is 45' on a reel. I carry another two pieces. One is 25' and the other 15'. Plugs at both ends allow me to plug in almost anywhere....Dennis
