I recently got my license and bought equipment. It funny to read here all and the same questions that went thru my head. This forum has been very helpful to me.
My recommendations are to get a mobile rig and learn to use it. The HT has too many limitations as the main radio. In additions you may not get to use it often enough to learn communicating with other hams. Driving around and using Ham is lots of fun. I had one trip to Moab without Ham and one with Ham. I enjoyed hamming in Moab alot. The terrain and activity lend itself for radio communications.
Installing a separate face plate will be easier and more versatile. You can install the radio where it is convenient to pull an antenna out. It is easier to run the connecting cable from the radio to the face plate, than running the antenna cable thru the car.
Don't install anything permenant until you drive and use it for a while. You most likely change you mind about the mounting once you use it.
I have Yasae for 2M and Kenwood for HF. The Yaseu plastics seems to be less robust than the Kenwood. After a year+ in the car, you start to notice the difference in materials, even if the features and the electronics are the same.
If I would to buy a 2M again, I would get the Kenwood for that reason.
APRS is very nice, but increase the cost. I would get it again.
Hope this help, not very technical answer but hopefuly helpful.