Can an LTM be connected to a Cisco FEX (fabric extender)?

Single arm implies connecting both internal and external interfaces on single switch Nexus vPC. In two arms, external interfaces are connected to upstream switch and Internal interfaces connected to downstream switch. So you are using two switches instead of one.

That is where I was confused because I was expecting two Trunks - external and internal traffic.

For example, External virtual servers VIPs 20.20.20.1, 30.30.30.1 (Trunk 1) Internal Nodes/pool members: 100.100.100.23, 200.200.200.34 (Trunk 2)

So you have only single LACP trunk connected to both 7010, correct?

I have the following questions: What happens if active F5 failed over to standby or primary vPC failed? Wouldn't this cause traffic disruption if the F5 does not have redundant link on both 7010?

Did you criss-cross connection to both 7010?