hamltnblue -
Congrats on getting Railpro, I'm sure you'll enjoy it. I've had it for quite a while now and have been really pleased. I have a bit of experience with the in's and out's of the system. On that note, a few of the things you mentioned above are not quite correct or would benefit from some clarification. I'll go by the numbers you posted:
1. All the files are meant to be stored on your controller. There is no reason to store anything on your PC, ever. If you have the HC-2 controller, the storage capacity was something like doubled over the previous generation HC-1. Once you download a sound file to your controller there should almost never be a reason to remove it. Once the sound library gets to the point where a very large number of sounds are available, then it may be necessary to delete some files from the controller to save some space. Basically just download the files to the controller, and leave them there in order to quickly transfer the files to additional locomotives.
2. There is individual control for each sound. Go to the "Settings" button for the locomotive, click on "Button Setup" on the bottom. On this screen you will be able to change individual settings for each function button for the locomotive (there are currently 16 usable function button slots). Scroll through until you arrive at the function you want to modify. To change the volume of individual sounds, there will be a volume slider you click on and adjust as you want. The same can be done for lighting to control dim, etc. Be sure to save your changes before running the locomotive, as a power interruption will revert all your changes if they are not saved. See pages 16-18 of the manual for more on user-defined buttons and how to change them.
3. Those items will likely be addressed in a future update. The HC-1 and HC-2 are essentially the same though. All the functions are the same. The difference is that HC-2 has much greater storage capacity, much shorter battery charging time, a much more powerful processor, and is cheaper. The HC-1 is no longer sold, although it is still supported.
4. This is true, and I've also heard that they are planning to allow users to do their own pictures in the future. In the meantime, they have other things that are keeping them very busy. They've been doing a lot with sounds and trying to flesh out the sound library more. In the past few months they've released the EMD 567 and GEVO prime mover files, and just today they released the Alco 539T prime mover and a dynamic brake sound. I know that they are working on horns at the moment as well. It all takes time.
Good to know about the batteries. I have not opened mine at all, nor do I plan to. However, should I ever need to it sounds like the batteries can be replaced by myself. Looking forward to pictures of what you've done so far.
-Kevin