It has ridges - pretty typical corrugated hose
Yes, the inner diameter is 1 1/2". It comes with a threaded adapter to connect to your 1 1/2" sump pump outlet. I actually McGyvered two of these hoses together to use as a backwash hose for my swimming pool. That required some extra parts.
It would require a 1-1/2" barbed coupling fitting and 2 hose clamps
I would not bury it below ground by itself. Run it inside French drains. At least the French drain will protect it and you can always remove the discharge hose whenever you want. Hope this helps.
Yes! That was the reason we bought this hose...
yes yes !!!!!!!!!!
Probably need to "solvent-weld" (AKA glue) a PVC fitting (1.5" female PVC pipe to male barbed 1.5") and a 2" hose clamp.