[Destroyer]

Nomenclature: (names)
Stern = Rear of the boat
Transom = the rear wall of the boat that the engine mounts on. (same as
stern)
Bow = Front of the boat
Rub Rail = the (most times) silver aluminum rail that goes completely
around the outside of the boat.
Deck = Floor
Cutty Cabin = the little cabin filled with bees.
Port = left side of the boat when viewed from the rear
Starboard = right side of the boat when viewed from the rear.
head = bathroom
bilge = inside bottom of boat.
bilge pump = a small electrically operated (most times) pump that removes the water that usually collects in the bilge from spray, leaks, fish, etc. and pumps it overboard.
cleet = (pronounced Kleet) = metal or plastic projection on the deck that is used to tie rope around.
line = rope.
anchor = heavy, metal object used to keep a boat stationary in the water.

This is a small list. There are lots more, but it's a start. To answer your question, a 150 hp engine is considered by many to be the ideal engine for a V20. The brand you get is going to be your choice. Everyone has their favorites. Some like Mercs, some like Hondas, some like Yamahas, some like Evinrudes and Johnsons, etc. Each brand has it's good and weak points.
Looking at your "before" pics I see you have a lot of work to do. I'm sure that the "after" pics will look amazing. Good luck and if there's anything you need to know or don't understand fully, this is the place to ask. The collective knowledge that is here in these forums is simply astounding in it's depth and breth. Good luck