I don't think anyone has been able to get the mouse to work on the XP3plus, no. The “virresh” mouse installs but does not “click” successfully.
And yes, you used to be able to install apps easily, but then they pushed a system update, and now you have to use ADB to sideload apps. Luckily that still works just fine, with the very minor caveat that USB debug has to be turned back on every time you restart the phone.