1) I heard from a not-necessarily-reliable source that installing a customised operator logo voids the warranty on the phone. Is this ever true?

2) What are the operators' attitudes towards people using a customised logo? I would assume that they don't much like it, as their logo is replaced. But, do you think, from a business point of view, that a company that had close relations with operators could ever execute a business plan that involved overriding the operators' logo with a customised logo, as part of a huge promotion - or would the operators likely kick up a massive stink and effectively veto it?

Thank you for your time.