A: They should start by running in intervals (which means walk for a bit, run for a while, repeat), then as the days go on, gradually increase the speed and decrease the walking interval until they're running easily and breezily.
B: Tom can reach his goal safely, as he is completely prepared for the challenges. As long as he isn't over-working himself and working a good amount each day, there's no reason he can't reach his goal within two months!
(hope this helped!)
