Hi and welcome.
I had a 2005 ES330, Black Garnet Pearl, Lexus 7 spoke Chrome wheels. I found that even though the manual called for Premium fuel the 330 ran very well on mid-grade 89 octane. Lexir is right, this debate is consistent, but mostly over the new Lexus recommendations on the new 2010-2011 editions. IMO, I would be comfortable using 89 octane, as I use it in my 2010 ES350.
Oil is a highly personal thing. The specs on a 330 call for every 5000 if I remember correctly. Whether to use regular oil or synthetic you will have to research for your self, since you will get no consensus on this forum. However, I am starting out my 350 on synthetic. Just my own conclusion.
SW is our local expert on detailing and paint care. It can be as involved and time consuming as you wish. Look at the detailing section. If your a do-it-yourself type, go for it. Me, not so much. I have mine detailed every 6 months @ about $190. It's worth it to me than spending a full day or more ruining a great paint job.
Hope this helps.
Paul