Regarding bikes, I had wondered what regulars might think. Realistically there's only three solutions; 1) you either have an arrangement to allow bikes in the vestibules, 2) You invest in more/better cycle racks at the stations, or 3) as commuters using several other routes do you force them to buy a fold-up bike if they wish to guarantee its carriage on their chosen train.
It's a difficult one. 1 makes the most sense for cycle-toting Hanborough passengers (with Combe and Finstock in the front compartment, and Charlbury in the rear), but I'd be (pleasantly) surprised if it was permitted.
2 - absolutely, and this should happen anyway... except that it effectively requires many people to buy two bikes, one for each end of the journey (until Oxford, Reading et al get Boris Bike-like schemes). And you're then leaving a bike on the Oxford (or wherever) cycle racks overnight and at weekends... and hoping it's still in one piece when you return.
3 isn't quite as easy as it sounds: Combe is in the middle of nowhere, Hanborough is at the end of a long cycle path from Witney, and Finstock is on a steep hill with fairly heavy traffic - none of them particularly suitable for little folding bikes. It's fine for people commuting from within Charlbury, but again, there are quite a few people who commute by bike from Enstone to Charlbury station, and again that's not a bunch of fun on a folder.
I wish I knew what the answer was.