I want to know if I will be able to use my old iPod accessories
It has a dock connector, so probably yes.
if I can afford the data plan
So wait until the week after it's out. Who says you HAVE to buy it as soon as it's out? That seems more of a personal question to me. Just look at comparable smart-phone plans. They're all up in the $80 - $100 a month arena. If you can't afford that, you probably can't afford a plan that'll support all the iPhone's features.
if it has a SIM card slot
That was covered IN THE KEYNOTE, SIX MONTHS AGO. Yes, it does have a SIM card slot.
if I can use music as ringtones
That'd be nice to know, but it's not a deal-breaker for me personally. I'm sure someone will figure out a way to hack that in, if it doesn't come like that, honestly. We've all seen what's happened with the AppleTV, and this will be MUCH more directly accessible.
That'd be nice to know, I agree.
I'd say probably not.
What this all really boils down to though is that you really don't need to know these things before it launches. After it launches, ALL your questions will be answered, and then you can decide if you want to get one. There's no reason you HAVE to get one on opening day, unless you've already decided (like me) that it's SO AWESOME that you MUST HAVE IT, despite whatever questions remain unanswered. Otherwise, just wait to find out. All will be revealed.
The pre-announcement in January was just to head off information leaking from elsewhere and build up a lot of buzz. I dunno if you've paid attention to the tech press, but that part DEFINITELY worked which is nothing but good for Apple.
