Good to see a fellow merchant.
I don't know off-hand about who sells what, but if no planets seem to produce those goods then you may have to wait until events cause a surplus, assuming there are events for those goods. I thought one of the major city planets might produce that stuff but maybe not. Would be nice if Ganim took up the slack for under-represented stuff, but maybe the point is to make these things a bit scarce? I dunno.
As far as guns I tend to go with short-range heavies like neutrons, and then fire when things get close. I'm one of those evil people who like to board, though, so I tend to just use neutrons to break through shields so my torps can disable the target.
Also, when dealing with threats I usually immediately cut my shields to half, because that frees up extra energy for the weapons. It does leave me a bit more vulnerable but tends to even out once I have enough upgrades.