1. My understanding is that, because you pay a mobile contract monthly in arrears, you are always a debtor of the company. All debts as at the bankruptcy date must be included in the bankruptcy - you cannot choose to exclude some. Therefore, when you go bankrupt this debt has to be included. The result is then that the company cancels the contract. I would be interested to know whether this actually happens to you. You can, of course, get a pay as you go mobile, or - if you have the money available - make an advance payment before going bankrupt so that you do not actually owe anything to the mobile company on the date of your bankruptcy.
2. The same problem could occur with your Virgin Media stuff. If you have a partner or close friend/relative who is willing it might be best to get the contract changed into their name before going bankrupt - always assuming Virgin will do so, of course.
3. The Official Receivers are not supposed to allow expenditure on broadband as an allowable part of your expenditure, but it is sometimes difficult to separate the broadband element of a contract from the phone/TV elements so it is not clear to me how this works in practice. But if you put down the cost including the broadband as one of your expenditure items be prepared for it to be queried.