1) No you can't attach one physical nic to multiple vSwitches
2) The pNics/vmnics are attached to the vSwitch where you can configure your nic-teaming. Those settings can be override by your settings on the port group level. If you have 2 x10gbit nics and you don't have the chance to virtualize them away into multiple virtual network adapter which appears to the ESXi as regular vmnic (e.g. EMULEX) there is in deed no reason for multiple switches.
The problem is that you might run into some issues that one network service (like vMotion) might have an impact on your other network services (e.g. virtual machine network). So if you want to seperate traffic / offer some kind of traffic guarantee you need to virtualize your pNics or make usage of the distributed switch and its resource pools