Most of the questions you raise in the first post you must decide for yourself.
If you have the time and access to the public library, perhaps you can look at the annual Consumer Reports automobile issue for descriptions of many models – including used vehicles – by brand along with price estimates, reliability and maintenance cost statistics and purchasing advice.
Edmunds & Kelly Blue Book are also well known sources of used car info you may find in the library as well as PCs with internet access for online sites like truecar.