there is absolutely nothing wrong with an aveo for the price, i have owned both a focus, a civic, and many other cars. the aveo is just as reliable, and cheaper.
to answer your questions..
1. the major things to check are for a metal thermostat housing, and check the fuse blocks for signs of burns. Its also good to have maintenance records, etc. there are a few other faults here and there, but they would be evident with a test drive and not overly common to mention them all.
2. the timing belt is a 60k mile service interval. so yes it can break every 60k if not serviced. you also want to verify if the water pump, tensioner, and idler pulleys were done. this changed in 09 when they went to a different engine with a 100k mile service.
3. i have had no issues with working on mine, its fairly simple. there is plenty of room around every part i have accessed/replaced. the parts are reasonably price for the most part and usually pretty easy to find.
4. the e-tec II engine code is L91 i believe.
5. i've parked mine for 2 weeks or so, there seems to be very little parasitic draw, however if your car comes with the standard korean battery i would through a better battery in it for assurance that it will start if sitting for 2 weeks or more at a time.
6. as far as i know ALL automatic cars come with a neutral safety switch now.. I can't think of the last car that did not. the aveo also uses the switch on the clutch peddle to prevent starting, as most cars that i can think of.
7. no such thing, on the 0 family engine had the timing chain, which i believe is the 1.2 liter version of the aveo. The family 1 engine design used in the aveo all have timing belts. BUT if you wanted the 0 family engine in the cruze and sonic (1.4t) i believe has a timing chain and can be a complete engine swap.
you could have answered all these questions just browsing the threads.