I've had a (lampshade) imac, and currently an ibook. The ibook was supposed to compliment the imac, but it ended up being my weapon of choice. I made the switch around the time Os 10.2, and haven't looked back.
It's as easy or as difficult as you'd like to make it, and finding programs for a specific task is a non-issue. You also have the option of running Linux programs if you know what you're doing, thanks to X11. Sometimes that's easy, and sometimes not-so-much.
Have a look at www.versiontracker.com - it's a mac shareware site. Simply search for the kind of program you want and you should see lists, usually with screenshots. :)
Most cameras are supported in OsX. Just because they're not at the Apple store doesn't mean they're not supported. I've had a Canon, a Sony, and a Nikon, and never had problems.
As for mobile phones, check out the compatibility list from www.apple.com/isync. Basically, if the phone supports the syncml standard, it stands a good chance of working with a mac. I'm even using a Pocketpc Phone edition pda, and syncning with the mac via a program called Pocketmac. It works better than Activesync in Windows. :)