2000 GA GT Heating problems

I have a 2000 Grand AM GT with about 59,000 miles on it. Ever since last winter, it takes an excessive amount of time for the car to warm up; and of course with that, it takes the same amount of time for the heat to be warm. I also had a mystery coolant leak earlier in the summer(about a liter of coolant all over pavement). Unfortunately, I couldn't determine where the coolant had leaked from, since everything was wet afterwards. Anyway, I had thought about changing out the thermostat thinking it might be stuck open, but was stopped due to the exhaust and heat shield being right in the way. I couldn't even get a universal joint socket in there.In addition, there's residue on my engine heads and block(around the coolant temperature sensor, and all around the gasket between the intake and heads and/or block). It looks as though coolant had gotten on there and burned on the surface, pinkish-orange and/or white crystals. Any tips are greatly appreciated, thanx.

Just an update, after calling PepBoys to check on the installation charge for the thermostat on my car, I was told $145; I thought heck no, I'll try it again myself. Once again, no luck with getting to the thermostat housing. It's like trying to get into fort knox or something. I removed the air cleaner assembly(filter housing), tried to remove the exhaust crossover heat shield(couldn't cuz the black coolant pipe was in the way), then proceeded to try and remove the black coolant pipe and eventually gave up. The problem is that I can't get a socket in between the bolt and the lower part of the exhaust going around the side of the engine. I have already purchased a set of Crowfoots from sears(open-ended wrench head with a square drive to attach to a socket wrench), however this wouldn't stay locked on the bolt. Does anyone know of a special tool or a very slim type of universal socket? I'm hoping I don't have to spend the 150 to change the thermostat, but I might just have to.