iRealSMS shows a timestamp for every message. When in the conversation mode just hit the edit button and the timestamp shows for each sent and received message.
TUAW has a fascinating article pondering the completely unsubstantiated concept that Apple, with it's $51 Billion in cash might consider buying Facebook, valued at $25-30 Billion.
TUAW -- The Unofficial Apple Weblog
I used Facetime with My3G the other day with my wife. I had no issues and it didn't seem to lag at all. My wife was at home on our WiFi network and I was at work on 3G. We talked for around 5 minutes without issue.
In that case you may have a defective unit. You should definitely take it to the Apple Store for inspection and possible replacement. I know my phones proximity sensor issues were resolved with a settings reset. If nothing's helping you could have randomly just got a bad phone.