Hello! Two way can solve it. One is using iCloud, if you have iCloud account, you just log in it in SE, you can sync the contacts which have been synced in 5S. Another way is use a program named iOSToto. It allows connect two iOS devices at the same time. Then you can use it tranfer iPhone data easily.
To reinstall drivers for Windows computer, it is easy, and there are many ways can help you. As for me, I prefer to use driver management utility to install drivers for my Windows 10 laptop. I think it is the easiest way.
You are not the only user to face with this problems. Many users have reported that bluetooth couldn't work after Windows 10. You can learn to fix bluetooth issue after Windows 10 here:http://goo.gl/DnKgek
Windows 10 need good specs for support. You can try to opimize your computer by yourself. You can turn off some effects in the UI settings, and uninstall useless programs for more space. Besides, you can use PC speeder tool like OSToto PC Speeder to help you speed up your computer.