For getting the display working, here is the write-up I did on it: https://communities.intel.com/message/225212#225212
My touchscreen driver isn't yet to the point where I am comfortable with sharing it. I just got the basic cursor moving and clicks working this past weekend. The code is a mess and really pegs the CPU. Unfortunately, I am going to be tied up with a big project for my job for a while so I will have to take a break from working on this.
The touchscreen project I am working on is similar to what you describe. I have a user interface with a few buttons and some simple state. I expect it will work for that. The screen latency is pretty high though. It is not quick and responsive like a tablet is. It isn't a huge delay but even small delays are easily noticed within user interfaces.
Search the forums for information about doing native C/C++ programming. There are a few different options from cross compiling to compiling directly on the Galileo. There has been good work done on creating more full-featured Linux images and making other libraries available. There are also good examples of how to use the linux device drivers from user mode. My recommendation to add to this is to take advantage of the Arduino C++ libraries. They are included with the Intel Arduino install. They can be used directly in a C++ program or copy/paste snippets out of it. I was able to build up my touchscreen driver by doing this kind of reuse.