Not on everything. Tax policy is exempt from this (veto applies) as is criminal justice.

Prodi wanted this changed but, in large part thanks to the UK, he got nowhere.

The Hun is always either at your throat or at your feet. Winston Churchill

A 50/50 (plus 1) or a 55/55 share would be better, yes. The double majority rule is now already in place but it exists in addition to the qualified majority voting according to votes, which only increases the number of veto points (the number of possible blocking minorities). See the wiki article on qualified majority voting.

What I meant by having the council only voting by double majority was getting rid of Qualified Majority Voting and only leaving the double majority rule, not necessarily moving areas which are now under unanimity to majority voting.

I am, however, a supporter of moving immigration to the co-decision procedure as well as limited aspects of tax harmonisation (though I more or less expect that the latter can only be accomplished in a 'core' Europe).

Turkish entry will not increase the number of possible blocking minorities, it will rather decrease it. But we will need to get some treaty changes regardless to keep the EU functioning.