As an smuggler I know what's problem with it - Worst is of course searching a station with a black market (especially in Imperial systems). In all stations (including those, which should be promoting piracy (anarchies)) are treated as an negative. Especially last one shouldn't be have right happen in anarchy stations (which promote piracy). If they deal with it, then should be easier and not harmful for anarchies.
With prices, I agree with you.
In all cases with piracy I agree - should be able to negotiate with NPC and be have more variety with it (and also for cargo available). For example, one ship will be have some salvage in cargo rack or second ship (in agricultures) also hostages and politician prisoners (which they should also add to fleet carriers which still can't be set to sell (same with rare goods)). Those variety will be of course extended during boom/investment/expansion states. And of course same should be in anarchy systems (which should be have more lucrative goods to piracy than in other systems during same state)
@T200 - For this I also agree - Hijacking ships, ransoming etc. also should be added. Especially first one should be added when Odyssey arrive - after hijacking a ship we can for example decide (this ship will be automatic set as an wanted regardless if this ship is clean or not), do this ship sell in black market or keep them (unless that ship is a part of a mission, which also should add).