I have a keypad linc (6 button) and can say that they do act weird. What I did to get mine to work is this:

1. set up the primary address
2. assign a button to the integral dimmer
3. changed all other buttons to non toggled mode and gave them address's

If you read the manual a few times you will get the hang of it. If it whacks out, reset it and try it again, after a lot of screwing around I got it work good for me.

As for the lamplinc, it sound like you have a signal or noise problem. You can try unplugging things (tv's, power strips, computers if one of these does the trick then add a filter to the offender. In general if you plan to build you system you might want to filter all of these throughout your home and consider a quality coupler/repeater. After doing this My whole home performs great (search this forum for lots of info on trouble shooting)