Hi,
Cubase LE/AI/Elements is an only one executable. So it depends only on the license, which derivate would start. If you have Cubase LE license, Cubase LE will start, if you have Cubase AI license, Cubase AI will start.
Cubase LE and AI are almost the same. AI has better integration with Yamaha/Steinberg hardware. Therefore I would recommend you to use Cubase AI 10.
Your 2nd question is answered in your duplicate post.