when in leaf mode, you'll only see 3-5 connections.

As an Ultrapeer (that's what leafs connect to), you get 30 connections to other Ultrapeers, and as many as 30 leafs will connect to you.

To be an Ultrapeer (it happens automatically), you need to be able to accept incoming connections, have decent uptime and connection speeds.

Whether you are a leaf or an Ultrapeer doesn't really affect your file transfer speeds or the effectiveness of your searches. The code tries to make sure that it works about the same.

However, since you have to have a good setup in order to be an ultrapeer, that's a good indication your friend's setup is pretty good.