The lagginess when editing is a VoiceAttack thing I'm afraid. I checked with a fresh profile and no plugins and it still lags when Elite is running. It does seem a very strange one, but I haven't looked in to it further.
The lagginess is odd, I have found that after about an hour or so it seems to start to behave and becomes less laggy, almost as if it's cached or something. It's still slightly laggy, probably 2 to 5 seconds on occasion before a voice command is initiated.
Yes it should talk between systems, assuming you've set it up using the 'configure' command. There is a bug in the current version in that it won't talk if you have a home system set, but if you clear that value it should work. If it doesn't then if you could pull the debug version of the code at http://www.mcdee.net/elite/EDDI-0.8.9d.zip, install it as usual, and jump between a couple of systems it would be appreciated. The debug log will be produced in %APPDATA%\EDDI\eddi.log.
I thought so, I've run the 'configure' command and I haven't set a Home System, as I'd read previously this could cause a problem. I'll try the debug version this evening and report back my findings.