WRT your question:
So is there an FAQ/how to to connect different VPCs in different regions? As far as I know you have to build a VPN connection between the VPCs to do that, any best practices document would be helpfull.
First, you might want to browse the documentation on VPC Peering (and no, you can't connect VPC's from different regions this way, just thought it is a good read)
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-peering.html
There is this documentation on connecting multiple VPC's
https://aws.amazon.com/articles/5472675506466066
Bottom line, if you are looking for AWS configuration questions/issues (especially VPC configuration questions), it is best to consult AWS documentation. You will get your best source of information from them.
Hope this helps at least a little
Cheers,
Dawn