Recent BSN grad going for MBA.. few questions

I graduated with my BSN December 2007 and I've been working in a 40 bed ER located in an urban area of Sacramento, CA.

My goal is to get my MBA at either UC Davis or UC Berkeley. I have taken college algebra and stats during my undergrad and i'm taking business calculus spring 09. i plan on taking accounting summer 09 and refresher econ classes fall 09. I'm doing this as preperation for the GMAT, which i need to take by summer 2009.

i would like to start the part time MBA program by fall 2010. i will be 26 when i start and 29 by the time i graduate. yea, it seems like its far away but its not like i got my BSN overnight either, it took years of planning.

How hard is getting into the MBA program at a UC school? does it really matter where i go? which classes would be most valuable for me before starting the program? as a younger new grad, i have very limited managerial experience. what challenges does that incur for me? where should i work until i get my MBA? i only have ER experience, should i stay there?

in regards the the GMAT, which books are best for preparation? i have the kaplan review book? what was you experience like with the GMAT?

does anyone that recently graduated with their MBA have any advice the wish they had before they went for it? i would really appreciate any input.

thank you