First of all, welcome to our club. Where you from?
To answer your worries, I had a similar "discussions" with my parents, but mine were along the lines of the age of the car... To battle this "factor" i got 3rd warranty from ASWN, because I bough mine from a dealer.
FTO's do require a little bit more money then your everyday barina... regarding part availability, most parts that do break down (alternator, starter motor) are pretty much readily available, if you live in a large city.
If you live in a small town, or plan to drive interstate heaps, then I wouldn't be driving my FTO, as even if a tyre goes down you will be left on a space saver.
Not many parts are interchangable, only some some parts from the Lancer, and Galants... there maybe others..
Now, Mechanics. It all depends on what your getting done. I have pretty much two mechanics, one that is close by, that does servicing, and one a fair bit away, that does technical stuff. It all depends on the mechanics experience.
Hidden Problems. Hmm. Every car will have one or two hidden problems, the only thing to do is get a mechanical inspection, and carefully look at the car. An important aspect is the service history of that car, which basially determines the condition of it. I'm sure once you find a FTO if you decide, some member here might be willing to check the car out.
Because the FTO, is almost 10years old. There will be problems, and these problems are very common in all cars. Such as Starter motor etc.
Another thing to remember, is that 100,000 is major service time, which can cost up to 1,500. (timing belt, cam seals) etc.
Regarding Insurance, use the search function at the top, it has this icon

... You will get heaps of info by searching.
Now, I can go on forever here, if you have any more specific question we are here to help.
Oh, for an FTO, that has say < 80,000km, tiptronic, and is in pretty good condition. my rough guess would be, anywhere from 15 - 17... Under 15 is cheap... If it's lower then that, I will be asking my self why.
FTO's, are very good value for money, and after 10 years, they still turn heads.
Boris