Be prepared for the unfamiliar. Should you have a problem with your assigned housing, contact the London Director or the London Administrative Assistant for help. Yes, whether you go through USD or on your own before you arrive or when you arrive in London. USD would not be able to help you find housing OFF campus. It will vary, depending upon whether you sign up through USD or directly with a landlord.
Landlords usually charge the first months rent for the deposit.
Yes, if you are staying off campus in an apartment . No, everything is usually provided. No, everything is usually provided or can be bought. This will depend on the landlord, check with the landlord, but more than likely yes. This will depend on your agreement with the landlord.