Like I said, I'd like to be able to maintain/adjust most of the components; if I could reduce the number of tools to do so through a careful selection of components and a bit of fiddling...well, I'd like to explore that possibility.
I figure I'd need/want to have a chainwhip and a track lockring tool. It seems that a track lockring tool might work with a bottom bracket lockring, so that would remove the need for a separate bb lockring tool. If it doesn't work, replacing the bb lockring with a track cog would, again, remove the need for a separate bb lockring tool, since I could use the chainwhip.
The bit about the pin spanner is not really an issue, just something that popped into my head as I was typing. However, I would like to find out which of the red and green Park Tool pin spanners works with the various self-extracting crank bolts out there; if I could use the same spanner on the adjustable cup and the 'caps' of the crank bolts, I wouldn't need a crank puller.
I understand that there is rarely a need to remove the fixed cup from a cup-and-cone bottom bracket (especially a British-threaded one, as it won't unscrew while pedaling), but I thought a cog over the cup would make a neat hack because the cup's wrench flats are (I've read) often quite shallow, and chainwhips are made to deal with tight/stuck cogs and freewheels. But I was worried, and rightly so, it seems, about damaging the bearing surface.