Nimbostratus
MVPcan't answer everything and hope some other might chip in on some experience from their setups. i do expect that most people don't touch this. if you plan to do so i would try to work with someone in the area you plan on changing the settings and do some testing to make sure you get out of it what you expect.
1) i can't tell you the difference between the wam and wom, there are some tiny differences but why ... do keep in mind these profiles might be newer then the dev central article you link to. but in general there goal is to optimize the TCP stack for usage on WAN.
2) cant help you here
3) this is the basis of the F5 BIG-IP. a virtual server has a client side (the TCP connection between the client and the virtual server) and a server side (the TCP connection between the virtual server and the pool member / node). you can select a different TCP profile for both sides.
in general you could expect a WAN optimized profile on the client side and a LAN optimized profile on the server side.
the Proxy Buffer high / low values are for that one side, it is actually the TCP receive buffer that is influenced here.
4) as mentioned i don't believe the proxy buffer is what you expect it is.
5) it depends on what you do. if you have a high speed LAN you could tweak it for that. if you want another WAN on the server side you might select a WAN optimized profile.
hope this helps you some.