Things that Pilot do to Annoy engineers? Well I don't think there would be enough room on the Server to get it in, so howabout breathe for a start!
Gaseous, some of the points you raised in your list are relevant, other are not, extended AOG times, we don't make them the suppliers do. Do you think we like keeping your aircraft sat around when we could get it out the door and earn money on something else?
Buying Parts from the most expensive sources? Well the amount of places you can buy parts is quite limited, most companies don't get any discounts on supply and it is only fair that a small administration charge is applied for Batching in and handling, which all takes time. Also ringing around 20 different people to find you a part for a couple of quid cheaper takes a lot of time as well, as for not seeing unserviceable parts, lots of them do have to returned as core deposits, or alternatively you can have the core charge added on, which trust me you wouldn't like.
If you have genuine concerns over your bills, then sitting down and have things explained properly with the chief Enginneer would be the best route forward, whinging on a website about it isn't.
Oh, and lastly, who do you expect to pick up all of the extra regulatory costs from the CAA?
Rant over!