VxLAN loops

Hi all

I have a question concerning two features to build Overlays between DC:

QinQ : this feature is simple to configure and transparent to end user, but

what about loop inconsistency/UDLD issues (STP sould work through QinQ tunnel but is it sure) ?

VxLAN : same question, how are loops avoided ?

Another question : I have tried LACP using QinQ but is it possible with VxLAN ?

I imagine this topology (see figure) :

Thanks for help.