Hi roerinaci - I was going to suggest you call the town and ask them to explain it to you, but you already did that

We did the same thing before we bought our house - If you look at the houses on the internet, most of them will have the amt. paid in taxes. I can't remember if it was just the MLS site that had that or the realtor sites. Either way, it will give you at least a ballpark figure to work with.
Also if either you or your husband/wife is a veteran, they do give you a break on taxes, at least in Littleton, and I think someone said that's true for the state (but I'm not positive). We weren't eligible for it this year because we hadn't lived here for a year when we filed for it. We had to file by April 1st, we moved here April 20th of last year, so we were short a few days
When you get to Littleton, let me know!