To answer to BGP problem about BGP and static route (big subnet) to Null 0 : http://lacuisinedegandi.net/post/2011/06/20/Quand-Null0-et-BGP-peuvent-causer-probleme.
A solution can be :
R2#sh run | inc track track 10 ip route 18.104.22.168 255.255.255.255 reachability ip route 22.214.171.124 255.255.240.0 Null0 track 10
Where 126.96.36.199 would be IP of loopback IP address of an iBGP/Transit eBGP router. So that, if it is unreachable, static route to 188.8.131.52/20 will be removed and announcement to an eBGP neighbor will not be sent.