Hey, hope my answer could be somewhat helpful to you.
With regard to your first problem, miui has LBE partially built in to the system(Not all the functions are included )
So when you install LBE, it may conflict with the system. I suggest you delete the system LBE yourself .
To your second problem, the miui development team is working in it right now. This bug should be resolved by next couple of weeks.
The third problem, you have to understand the main MIUI site provides miui rom mostly to Chinese users. So maybe you should try out those modified version at the xda forum. Those roms should include the proper GPS configuration file in the system.
In regard to your apps to sdcard problem, in the initial release of miui for i9100, the majority of people have a lots of FCs, and the development team discovered this is mainly result from "apps to sdcard" function. So they eventually disable this function in later builds.
The last two problems should be fixed in the next couple of weeks.
PS: Google translate really sucks, we don't understand the Chinese translated out of that thing....
PS2: Don't put hopes on having those bugs fixed really soon, MIUI always treats their own Xiaomi Phone in priority.