Don't worry too much. Even if it falls off the windshield, it will not be the end of the world. But seriously, the power cord will save it from falling. Already happened to me a couple of times.
I suggest you apply a thin film of oil-based lubricant (I use petroleum jelly) on the edge of the suction cup before installing on the windshield. Dont use water because it will evaporate and will just push the cup off the glass.
As for the tint, you have no choice if you are using the suction but to hope it wont pull off the film.
Or you can buy a rear view mirror mount like this. I bought mine from Lazada for less than 150 pesos. My dashcam is G1W and I bought something for Xiaomi Yi but I was able to make it work.
Re: video file length, yes dash cams records videos and saves it small time intervals. This has two purposes. One is to enable loop recording function which requires erasing old video files. Second, it allows users to save only the videos they deem useful.
Imagine saving the video of your whole trip in one single file. Buti sana kung 40km trip lang pero kung papuntang Baguio. Mahirap i-review ang large files.