Where is the thermostat located on a 2006 Volvo S40 T5 AWD (gasoline)

Attached are two pics. One is the pic of the reservoir where there is a small crack which I was told was due to pressure build up over time. Second pic is of the area of where the coolant leaks. It seems to be right below where the coolant reservoir sits. So I'm guessing near where ever the thermostat is located? Leaking somewhere behind the front passenger tire area. (This pic is not from my car ; Google pics. I'm at work and don't have my car with me) The third pic is of the crack on the reservoir tank - looks bigger than it really is. Let me know if this helps at all.

Thank you so much. Not so much that I want to replace it as it is what the Volvo mechanic told me needs to happen. He said this is one of the reasons your radiator fan sometimes runs even after you shut off the car. I've heard the fan before once or twice and it has always been after a long drive, hot summer day or a combination of both. I had a hunch the thermostat might be under here when I was snooping around the engine yesterday. And you are right it does look like a mess to take out. I'll see if I can get to it over the weekend. Otherwise maybe find a reasonably priced mechanic to do it for me. I'll let you know how it goes. I truly appreciate your responses. Thanks again.

Update: Tried to take the air box out myself and attempt failed :) there is way too much going on there and I didn't have the right tools. Took it to a mechanic who said he would do it (since I had the parts) for $70. I was there the whole time he was working on it and changing the cracked tank. Thermostat has been changed as well as the tank and no no more leak or car randomly shutting off. **BUT** now I'm back to my original problem that I've had with this car. "Reduced Engine Performance". Volvo Mechanics have worked on this issue multiple times and clearly haven't been able to fix it. (See attached Pic)
In the process of taking out the air box we had to unplug some of those connections listed.
#1 cover
#2 vacuum hose (I believe that is what it's called)
#3 electrical wires (looked to me like a computer once #1 cover was removed)
#4 hose (also remove so I can change the spark plugs)
#5 small hose connected to the back of #4.

Could this have caused that "Engine performance reduced" message?
Few things to note: Seems like the turbo does not kick in at all. Speed is very slow to pick up but once I reach the MPH I want to be at it holds steady assuming there are no hills :)

I've turned the car off and the message sometimes goes away and I can drive normally again. However, sometimes doing that doesn't work either as the message will come back up after a few minutes if not immediately and RMP doesn't want to go above 3k even if I have the gas pedal to the floor.

Could all this be a Turbo issue? Does it sound like it needs replacing as well? It seems like every time I have something "fixed" on this car something else goes wrong. I'd love to truly get it fixed and get rid of it before I hit another snag.