I'm sure you can, all hotels on Disney property are open to the public even if you are not a guest. They do have sections which are guest only accessible like the pool and recreation areas.
Restaurants and shops and normally open to all foot traffic
Yes, it's just like any other Disney hotel, anyone can go anytime to visit, shop, dine, etc., but the pools are for hotel guests only. The pools are not gated, instead you have to be wearing an Aulani wristband in order for the lifeguards to let you swim in them. To get the wristband, you have to "check in" at the Kawale Korner (where you can pick up your pool towels) by presenting your room key, then they give you a temporary plastic wristband for the day.
I can tell you for sure when we were there last week they charged us $35 overnight for the valet and for self park I was told it would be exactly the same $35 for overnight, so naturally we did the valet. I guess if what you read is true then I would think it applies to the valet, but not so sure about the self-park. For self-park I'm guessing they would charge a few dollars per hour up to a certain number of hours, then once you exceed that max # of hours then they charge you the flat rate of $35. Otherwise hardly anyone would do self-park. I can't say for sure, that's just my guess.
Last edited by 3IAlienKid; 10-18-2011 at 10:09 PM.
Thought I would update this. My friend just went to pick up some things for me. She was told that the first 30 minutes are free. Not sure what the cost is after that. She made sure to get in and get out in time.