Ever since I tried pea-based protein powder I've come to think that peas don't make good drinks. Maybe I should reconsider..

never seen any but now im interested in trying it

There used to be a brand called "Ripple," and it was pretty tasty. IDK if it's still available

Absolutely, you just need to account for missing fat if the recipe calls for a significant quantity. I just toss in some extra vegetable oil to compensate.

Yep! Usually ratio needs a bit of tweaking for the recipe but it works for things ive tried

By itself, it's not noticeably different than water. The flavor is subtle enough that anything will overpower it. It lacks (but not entirely) viscosity.

Coconut milk makes a superior gravy texture as long as the gravy is strong enough to hide the coconut. You can make sawmill gravy out of coconut, but you'll need to add garlic, salt and pepper to hide the coconut.

None of the _____ milks properly work with eggs.

Cashew milk has a great mouthfeel but separates when heated.

All that said:

The plant-based heavy whipping cream you can get from MOM's Organic Market will absolutely work in sauces, gravies and even whipped cream. but it's full of stabilizers to make it happen (which i'm find with personally)