1: No, not really. Nosecones are rather pointless, although Squad says they improve stability. You should add winglets (AV-R8 Winglet is best) onto the sides of your rockets to stop quaking and overall fly smoother. Turning on SAS (press t) is the #1 thing for stability though. 2: RCS is important for maneuvering well in space, but isn't necessary and can be gone without. You can wait on it. 3: If an engine has vectoring, its easier to steer while on. Useful for main stages, but not really a concern otherwise. 4: Vanilla ksp doesn't give many stats. Mods solve this, but overall it's not that important. Weight is important for making symmetrical rockets, though. 5: The Probodyne series is much better in terms of probes, and the stayputnik really isn't that useful. Don't bother with it. In terms of interplanetary travel, you should work towards unlocking nuclear engines.
