I'm not sure, but my educated guess would be that the deja vu stuff is probably just a result of your "heightened awareness" now of things around you since your diagnosis. You might notice yourself getting more "gut feelings" about things sometimes, too. A lot of visionary businessmen experience the same things you are describing, and that's what they use to their advantage in being successful. So, if utilized and harnessed a bit, those "feelings" might be a gift!
I get the deja vu feelings a lot. Always have. But I never really connected it directly with a health condition or MS at all. I think it's something else altogether.
No.....You're not going mad. Rest assured on that.
Robin should be around in a bit and should be able to chat with you, if you like, regarding the sports limitations that you feel you now face. If I'm not mistaken, I believe Robin has had to deal with that sort of issue, also, as he was/is a highly physically active person. Feel free (as he suggested) to PM him, also.
EDIT: Bromley..........are you on an AED at all? (i.e. anti-epileptic medication) If not, and the deja vu feelings are bugging you too much, you may consider speaking to your doctor about it. An AED can sometimes (or you could even say most likely will) help to calm that sort of activity in the temporal lobe (from what I understand).