In reply to joekoruk:
Hi!
Stayed in Yosemite last week so hopefully the following is a bit useful.
Camp 4 was crazy. We turned up at 5am to try and get in. We were number 41 in the que. There were 20 spaces. Needless to say, we didn't get in that night. Started queing the afternoon before to get a space for the next day. Whilst technically not allowed (as you are not in the camp boundary, you are considered to be 'wild camping'), most nights, rangers seem to turn a blind eye to people 'hanging out' (ie. 'not sleeping') in the Q. There were 15 spaces that night, 8 the day after and 0 the day after. Having said that, September is crazy busy as it's when they allow stays of 30 days from. From what I've heard, May is much quieter but, as you mentioned, length of stay shorter.
Wild camping is not permitted in the park but from chatting to other folk you can sleep in your car OUTSIDE park boundaries perfectly legally.
We stayed at a campsite en route near Coulterville but most campsites outside the park are at least an hour's drive from Yosemite Village which adds a lot to your day.
As for bears----we got to the stage where we were disappointed we HADN'T seen one! Everybody we met told us we we're guaranteed to see bears. We eventually saw 2 Cubs on the way out. The park itself provides bear boxes at all carparks and campsites to put food in. Use them and your car should be fine. The park will fine you if a bear breaks into your car to get food! The outdoor shops all sell bear proof food cannisters to take camping. Spiders and snakes? Didn't see any but I guess all the wildlife will be more prevalent in May after Winter
Not sure I can offer any more but hope that at least alleviate bear anxiety
Have an awesome trip, it's ace!