1) Yes, people use tweets to report bugs all the time. The problem with nitpicking is that anyone can pick your nits back, which leads me to...
2) Yes, they will, but that won't necessarily repro the bug without knowing which type of device it's running on, so at the very least they might need to check several different devices, and even then other factors can come into play that go beyond basic device configuration.
I'm sure, given that this appears to affect at least a significant minority of users, that Apple will be all over it and will find a way to repro it in relatively short order. Yet, at the same time, it's obscure enough to have escaped their no doubt reasonably robust QA processes before release, so it may well be there are some wrinkles to reproduction that aren't immediately apparent.