the timing belt should be done @ 100,000km's however as it is common in Japan to wind the K's back, if you have an early model car I would reccomend doing it as soon as you can afford to.
As far as Oil goes, there are plenty of FAQ threads available for this info if you do a search but I only use 100% Synthetic oils. At the moment I'm only using Motul 8100 X-CESS(5w40) although Turbolight 4100 and 6100 are both good oils as well. Have a look at http://www.motul.com.au/product_line_up/4s.../4stroke01.html
The general rule of thumb I stick to is buy the best product you can afford to.
Hope that helps