Incoming MPhil student – a couple of questions about accommodation and travel

Hello everyone.

I'm an incoming MPhil student this year, and I had a couple of quick questions I was hoping someone could help with:

1. For college accommodation, how is the rent usually paid? Is it monthly, quarterly, or some other schedule?
2. I'm an international student and will be landing at Heathrow. What's the best way to get to Cambridge from there—train or coach/bus?

Thanks in advance for your help!