In the OTT solo campaign, pilots were able to switch planes as later types came into play. We were playing a chronological campaign, so this made sense. With our game, it could make sense to have some limits based on rank, for example a Lt. not commanding a 1st rate. I don't know how restrictive we should be given that this is for fun, and is not a tournament or competition.
As far as captains remaining with crews or bouncing around, I would say the latter. This would require a bit more admin work on my part, and clear communication following AAR requirements on all of the players' part (I will spell out a few items that need to be in every AAR similar to the Butcher's Tally we use in WoG - makes record keeping much easier).
As far as receiving recognition for being a privateer, you might find this
link useful.