Do the original terrokar cards work for Curse of Stahd?

If I play a Mountain Dwarf with Heavily Armored feat, am I meant to use a shield?

Does the 2nd pt. of Shield Master function against spells that can only target 1 creature?

For aquatic combat purposes, is a grappled creature considered to have a swim speed?

Can a Find Familiar fey octopus breath air normally?

Does Evasion work against spells like disintegrate where you save to take no damage?