I tried to find your previous suggestion but you've posted so many replies I didn't waste the time.
1) Terminating queries is what the TTL is for. But also I pointed out that the HTR (if that is what it would be called) would eventually be rounded down to zero after so many divisions.
2) I'm not sure exactly what to do about abuse, the purpose of putting the idea on a forum is for other people to do the hard thinking work for me
3) Reading your post has given me another thought. Older clients that ignore this new field would not change it (or maybe even lose it), thereby extending the life of the query. I think it would be smart to leave in the TTL not just for compatability reasons.
Now I just need someone to convince the 'THE' people to make appropriate changes to the whole of gnutella. Should be easy enough.