Welcome to the forum
The main pitfall is that you didn't get to put the miles of fun on for the first 100-120k mi lol. Most of the problems you run into are the normal problems that we all know about like the t-stat housing leaks, IMRC box problems, and a few other minor things that are easily fixed. Also don't forget the all important t-belt change that we tend to recommend doing at 60-80k mi. Clutches can be bought for cheap at partsgeek.com for a tad over 300 bucks which is a steal compared to everyone else, but most of the factory clutches last a long time, one local member has over 150k mi on his or at least I think it's that much, I forget but I know he has almost the same amount of miles on it as I do on Ole' Yeller (my yellow ZX3 which was my first focus). The transmission seem to be very durable though are getting hard to find and are not rebuildable like other transmissions. I have never seen one with power window problems on here that I can remember but they share the same parts as a normal focus with power windows. The head units do wear out and majority of people just replace them with a aftermarket unit though a lot keep the factory sub and we have How to's on how to do that HERE
are some sticky threads to read over that can answer a lot of questions and point you in directions with the SVT also.
We have a few members on her that have much higher mileage than what your asking about and I even think there are a few 200k mi ones on here as well.
I'm also glad to hear you like them and are collecting them. So many of them are just parted out now and most of the time cause people don't want to fix them, a lot of times from a broken t-belt or something like that
. I personally want to try and save everyone I can but I can't. I was lucky to save the one I have. HERE
is the thread for mine I made, which will be updated as soon as the all important income tax check comes in.