hello Grief

Actually your experience with driving shouldn't severely affect your choice of car... i guess what's most important is to drive carefully yah? Nothing shld happen in that case... and if anything does happen, it'd be an insurance issue rather than a new car/old car issue. A new car is definitely more worth it than a used one, unless you are on a tight budget and would want to get more car (metal/size) for your buck. People used to buy 2nd hand to avoid the mandatory 30% downpayment for new cars. Now that is gone, and also how new car prices have dropped, it's definitely more worth it to get a brand new one.
Made in Thailand shouldn't be a problem, as many forum users have said

due to the AFTA, more Japanese manufacturers will be assembling their SEA cars in Thailand. The City/Accord (City is a 5-door Jazz) Vios/Corolla/Camry are built there already. Major parts and the designs still come from Japan, but labour, component, logistics costs are lower.. so why not?
Mazda 323: The replacement model's coming in next year. These are leftover stock the local dealer's trying to clear. It's up to you whether you fing this worth it or not.
Hyundai Matrix: Low price for a 1.6l car... though i reserve my comments on Korean cars, I believe it's under-powered and the rear seats are tad too small.
Nissan Sunny: Another popular car, though I agree with you that the rear looks ugly. It's supposed to consume a lot of petrol, if that's an issue with you. Actually rear drums aren't bad ideas, they are just cheaper than disc brakes.
Proton Wira Avoid at all costs! An early 1990s Lancer and if you are looking for reliabililty, don't look at this car.
Manual or auto? This is really up to personal preference. If you'd like a manual, my advice would be to borrow a manual car and drive it around for one day to gauge the feel. Hah, as for not wanting to drive a manual after using an auto, well it depends on whether you'd want to or not! An auto is definitely easier to drive, but I still prefer manual cars... heh.
Good luck with your choices!