Ok, so what i'm gonna say is just my personal thoughts and ain't a general thing...
For ①, that's true. It isn't easy to lend a hit with railgun either from far distance nor close distance especially if you are against smoky; it is a true pain lol. But i do know few tips that can help to increase the chance of hitting your enemy; if you're far away, try to find a wall, then act like a sniper (shaft) ; but railgun have an advantage over shaft, you can move. Stay hidden in the wall and press your fire button when you spot an enemy, then you can move at the right moment right before the railgun shot is out and hit the foe, it is kinda impossible to counter that from a far distance, but still a chance. you can manage to learn that "railgun timing" using either sound or playing too much. Practice is the key for everything. Now for mid or close range, simply put: wait for them to waste their shot, then punish. OR, you can easily go and dive in, then use driving skills to make them waste their shots (like pretending to go forward and instantly go back or move in a random way etc...). Those kind of things are so casual on XP/BP, especially on BP where you will notice how wasps can make u miss the shot so easily without even bothering to use theirs.
For ②, in CTF, you have teammates; don't forget that. But if you wanna relay on yourself, then first you will have to try put them in 1 shot instead of kill, if you kill, then they might just respawn behind you and, as you said"Bam. Dead " ^_^ , make sure you attack with teammates, you're not alone. And for those railguns with 10 KD ratio or so, they either play usually as deffence or campers. You can do that too, just forget about flags and keep killing... which i honestly don't like xD (my K/D proves it :ph34r: :ph34r:)
DD isn't the solution for everything.. well maybe works but not all the time; the enemy can have full supply but only with teamwork and skills, that enemy goes "poof" in a few moments.
But all that is just words, when it comes to reality; what matters is Practice, practice and practice, all that comes with time :D :P