You should consult your doctor. That's the best advice you can get. Because it's different with everyone.
You'll be fine. I did all sorts of crazy stuff when i was pregnant. Once that egg is implanted, you aren't going to shake it loose. Not early on anyways. Once you're all puffed out and whatnot, i'd be more careful then.
It depends on how much you exercised before. In general if you didn't now isn't the time to start. Light yoga and stretching, walking and jogging should be ok.