Hi again,
Answers to your questions:
- Yes, Viber will support MMS-like features (pics, sounds, etc) in one of our future versions. I will announce it here once we have dates.
- Unfortunately, at this stage we won't be supporting HTC Wildfire, and that it is because we encountered severe issues when developing Viber on it. We apologize for the inconvenience

- About the battery drain: are you sure you isolated Viber in order to determine that this is the certain cause for your battery drain? We tested it here in our labs with several devices and except for when making a call (when it is natural for the battery to be used), we didn't notice any significant battery drain.
- ROMs: At this stage, we don't support custom ROMs with Viber (we might add support for *SOME* ROMs in the next several weeks). As you can see, running Viber on a customized ROM results in various side effects, some of which are severe, but unfortunately we can't afford to support ALL those ROMs at this stage. As I suggested in the past, you might want to contact the ROM developers and ask if any adaptations could be made there in order to support Viber.
- Viber needs to run in the background in order to receive/make calls. It is a communication app, and this is what it's meant for, when you think about it.... However, according to popular user demand, we might be adding an "Exit" button soon, that'll shut off the app.