Hi,
CUE-AIM can be hosted on the 2801 ISR. Actually you could use even smaller router live 1721-V, 1751-V, but these don't support CUE and are going end of sales soon if not already. So these are better for buying used gear.
you need a voice bundle, a BRI card and nothing else basically nothing talk to your reseller and if unsure come back here with the proposed list.
Try to get also a smartnet contract so you can register for CCO download and upgrade code as you whish.
The Cisco wireless phones are good if you like them, else a traditional one, better if with ISDN will work as weel. Watch out the the linksys phones aren't supported by CME right now but they will eventually.