If I renew an expired domain and then transfer away, do I lose a year? This happened to me, currect registrar hasn't bothered to reply in 48 h, so I searched the net and at least some registrars have 45 days policy. I cannot find this clause on the current registrar's site.

I believe you HAVE to stick with the registrar for atleast 60 days before transfering...

60 days after registration, but after a renewal are 45 days, if transfer before those 45 days, you lose the renewal

The 45 days was put in place by ICANN. Some registrars abide by the policy and some add the extra year. So you're best to ask the receiving registrar what their policy is.