Actually, the timing chain isn't considered a wear item, and has no (factory) reccomended time that it should be changed. It's been known to have problems though. One of the most common is the guides wearing out on older s13's. It's usually reccomended to leave it alone unless you hear chattering which usually means it's going to go, and then have it replaced quickly, because the KA is an interferance type engine, meaning that when the chain goes, the pistons colide with the valves.
as for Q #6, I'm 6'1" with pretty long legs, and I don't have any problem fitting in the car. It took me a few weeks to figure out how to get in and out though <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>