go to line 94 in weapon.cs of Weapon_AimRocketLauncher,
you should find:
%speed = 0.4;
change that to whatever you want, 1 being undefined curve (it just points in the direction) and 0 being no curve at all
0.3 or 0.2 should be fine
homing rocket launcher, I don't know :/
I could find out, but I'm lazy