I dont have a fuse on the invertor, it has it's own built in overload switch so it you overload it automatically shuts off.
The alternator is whatever is factory on the 3/4 ton chevy with a 6.0, looking on napa's website they show a 145 amp one as the standard replacement, so i guess thats what it is.
I have to have my truck running on the bigger items like the table saw or chop saw, but it will run the grinder, drill, lights fine with it off you just have to make sure you dont run the battery down to much which is part of where the 2nd battery comes in, just a lil bit of extra juice for using some of the tools like the saws that require more power at just start up.