whatever domain you want to use, you can use single label if you want pc1.locadomain - I just am not a fan of it..
As to why something didn't answer broadcast, firewall comes to mind. if wireless AP isolation comes to mind or just dropped traffic.
pc1.riahc3.mydomain works as well.. The possibilities are pretty much endless.
doing \pc1 should work just fine - again understanding name resolution is the KEY!! To troubleshooting such issues you might run into. Most clients will use different methods be it windows, os x, linux, bsd, beOS, etc. etc. You just need to understand what order and which ones your clients use when you want to resolve host names.