Someone more local than me will be along shortly hopefully. But, yes to park and ride – parking is very tricky in the middle of town and P&R easy enough. That said I only properly know the ones coming in from the South Side, but Pear Tree Park and Ride should be fine.
Most of Oxford is really easy on foot once you’re in the centre – all the colleges, museums, libraries, famous boozers all within easy reach of town centre.
Only commonly visited part that’s a good way out is the Cowley road, the ‘edgey’ bit of town where music venues, interesting food etc is to be found.
Bodleian Library, Pitt Rivers/Natural History museum, Ashmolean for museums etc Don’t know many pubs sadly, but Turf Tavern is great and Eagle and Child is the JRR Tolkein pub.