In reply to Offwidth:
Depending on how obvious your van is, there seemed to be lots of people staying in vans in the park in October (you can get busted though, so think twice).
Lots of people post for partners on the camp four notice board. It's worth checking the current booking rules, I think they might have changed recently.
A bit of aid practice in the UK is worthwhile, especially bolt ladders, lower outs, using skyhooks/camhooks, jumar following. I ran a course for some guys earlier in the year with Yosemite bigwalls in mind. Worth practicing crack climbing too.
Quite a lot of the easier walls don't require a portaledge (S Face Washington Column, West Face leaning tower, The Nose). Haul bags are cheaper to buy there than here.
Belays are for the most part all bolted and seemed pretty well set up for abseiling (70m rope can be handy).
Free WiFi can be found at Degnans deli (between the store and ranger station) and at Yosemite Lodge Bar (other side of the road from Camp 4). The lodge WiFi was much better when we were there.
If you have any specific questions feel free to send me an email.