Re exercise: i've found it totally fine, though sometimes if i go to the gym i've felt a bit lightheaded and had to stop earlier than i would have done before i started exante... I run a lot too which I've not had any issues with... agree with kenshin - just drink extra water on top of the recommended amount or youll dehydrate....
I wouldnt do excessive or very intense exercise though, as if you burn too many calories while on such a low cal diet you could end up with things like hair loss etc..
Ketosis is different for different people, it took me 3 or 4 days when I started originally, but I know other people it can take 2 weeks. I didnt find it had the benefit of getting rid of the hunger which some people get, so I think everyone is different.
The first week on a vcld I was really tired and crappy feeling, so if you've just started recently then don't worry it does pass. I find after a week I feel much more energetic..!