That really comes down to what you want from the bot itself, and what you really need. As Jaggeh has said.
XP wise, is to only pick up legendaries, nothing like blue/yellow or gems.
GP wise would consist of a well known GP profile, GP bonus gear and gems, and also picking up all gold which is dropped.
Trash size, once again, you need to decide based on what profile you wish to run. 2-3 is usually optimal unless you run Bounties.