I see that #93 has two kills this set. What's the record?

It's an unhealthy record to shoot for since people will start sniping kills and that looks like collusion. That is the reason we don't have a kills leaderboard on express.

Solo kill tho I have seen people do 3 in a set and I think some people must have done 4 at some point.

It would be possible to do 5 for sure if you pick targets just for ease of killing them, but thats pointless. Killing 2-4 people that deserve it in a set is a job well done, imo. As is killing 1 and still getting top 10. :)

i think celphi holds most kills on express set record. how high it is that you need to ask from him or find celphi's kill-thread and count them by yourself.

Should be the leaderboard for most annoying (Aka Kills)

I've had 3 few times, you can do 4 if the conditions are right.

and that's why there isn't 1 and won't ever be (devs have said so).