I have 2 questions, both relates to routing protocols. How route/path looks like when there is L2 switch inside path. I mean with turned on either RIPv2 or OSPF. To clarify I must say there are 2 paths, one through 3 routers and second on through Router -> Switch > Router. This may not be the most precise question ever given, but...
Both OSPF and RIPv2 use multicast for neighbor gateway discovery - normally/by default a switch is transparent to that, so it has no impact.
Of course, multicast is only propagated across a broadcast domain, so only gateways connected via L2 can be discovered. However, these routers should propagate routing/link state information from more distant networks, so the whole topology can be discovered.