Stick with one of the big providers, BT for example, but you will need to connect the phone line first. Mention it during the process and I am sure they will help you out getting connected. Unlimited downloads is good idea.
commando if you are wearing proper running shorts, the ones with a liner in them. If you need or want more swingage control then lycra shorts underneath help. I have done a couple of marathons with this arrangement and it is fine.