How much downloading do you honestly do now? You're moving in with the missus so I'm guessing even less than now!

I wouldn't choose by no download limit as you could restrict yourself from a good service. We have a 15GB monthly limit and considering we work on the web all day plus personal surfing at night/weekends, we've not hit the limit yet.
Anyhow. We're on fast.co.uk after out 6 week nightmare with UK Online. Fast are second to none. It's great when you phone support (which we never do now, but obviously did at first to get started) and it's answered within 2 rings, compared to UK O which I once sat on the phone waiting for over an hour.
For routers, I'm a fan of linksys, however we have a belkin one here (with linksys modem) and admittedly not had the problems I usually associate with them. My hint would be, work out which one you want and check on Amazon as they can be much cheaper there if you catch the right moment.