I've heard that it's advisable to clean out the turbo. What does that actually mean? Is it cleaning the filter or the turbine itself? And also what is the optimum time to set for a turbo timer?
I don't think you can clean the turbo itself. Unless you are taking it off to be rebuilt. As long as turbo is in good condition, no smoke, no shaft play, no oil sip, no winding noise, you should be good. Just make sure change engine oil frequently, because the engine oil in the engine is what going through the turbo to lubricate the ball-bearing/journal.
Definitely need to keep the air filter clean. Imagine breathing through a dirty respirator versus a clean one. Same concept.
The turbo timer today has built in features that calculate your driving time and load, then it set the turbo timer base on that conditions. Other wise, 5-10 minutes for "normal" driving, more for track or "hard" driving. Basically the longer the better.
I do believe if you take good care of the engine or turbo,you will get what you deserved in return. Just like your body :)