1. i dont think you can. i think you have to format your HDD and do clean install of windows on the SSD and simply reinstall programs(i did that a few weeks ago because my pc was slowing down).
2. probably not.
3,the steam games will work you just need to change your main steam folder in the setting of steam.
3.no but you can save them or if you have windows 10 you can change location of those folders in their properties.
if your windows copy is connected to microsoft account you can activate your windows license after installing windows.
the search function should unless the windows install is broken somehow