#1 Over distance it can be hard to distinguish who is an enemy and who is not. This was brought up and discussed in the closed beta. In close quarters it's pretty easy to tell.
#2 It depends on the character you were attacking with that flame thrower. Some characters have more health than others. The flame thrower is actually one of the worst weapons in the game ATM. I've heard it might not be working as intended. Same with the chem sprayer. I could be wrong, though.
#3 Some snipers will 1 hit kill you if you're a free infantry unit. (I.E. The Ramjet.) Beyond that, the only way to get one hit is via headshot. Although, it may seem like you're getting 1 hit killed when you're actually not. It is possible you might have taken a lot of damage before that sniper hits you. You just might not have noticed it.
This was also brought up several times in the closed beta in regards to the player's awareness of their health. In my opinion, some steps need to be taken to help make players more aware of their condition. By the time the screen has red borders around it, you're pretty much dead.
#4 Yeah. That can be the way it is, but I've seen games get turned around with a good bit of teamwork, or at least the odds get evened.
Renegade X has a bit of a learning curve to it, considering it's not like any other shooter out there in terms of gameplay. If you wanna try and get good at something unique and fresh, stick with it. Otherwise you may as well go with the flow...