can this guy do nothing but jump and shoot? i mean cant you crouch and shoot, shoot up/diagonal or something?
is assume you're talking about model X, you can charge your shot (full charge gives you 2 shots to release), you can dash and that's about it. You can get more models later that will give your other abilities.
You can only crouch in human mode.
are those enemies respawning all the time?
Yup. It's actually both good and bad.
will you get more energy container later in the game?
You will get life upgrades later on and subtank containers that you can refill with recovery items that you can use later on.
i.e. boss battles