I have a question here.
IF Switch A Gi0/1 connected to Router A Gi0/1 and Switch A Gi0/2 connected to Router B Gi0/1 , will they....
cause a loopback when Router A and B are connected to each other for redundancy link through cross-cable??
Based on the information you have given you should be okay with this setup. We run a similiar setup in our data-centres ( altho we also have redundant switches ).
A loop is usually caused by a router pointong back to the router that has just forwarded on the packet. This should not occur with your setup.
The switch should see 2 equal cost paths to all networks beyond Router A & Router B. Router A will see 2 paths to any network on the switch, one direct through it's connection and one via Router B but the metric should be better for the direct link.
Are you seeing issues in your network ?