Thank you very much for the advice. I was very lucky in that I ended up getting the kit I bought set up and running on the first shot, so I didn't end up learning very much about the printer. Instead of cleaning the nozzle, I decided to just replace it. I thought this would be easier, but it looks like I was wrong. I thought everything was good after I replaced the nozzle, but after testing it out I saw plastic oozing out of the top and bottom of the heat block. I tried taking off the hot end, but just got the wires tangled. I removed the extruder assembly from the x-axis and was able to get the hot end off. Next, I tried to get the teflon lined barrel off the heat block, but ended up shearing it in half. At that point, I didn't care about preserving the threads anymore, and tried to just twist the rest of the barrel out. Naturally, that ended up shattering, leaving me with a chunk of barrel still in the heat block. I tried drilling out the remainder of the barrel and running a tap through it to clean out the rest, but I think I may have just destroyed the remaining good threads in the heat block. After all this, I'm left with a few questions.

Just how close should the nozzle be to the bed? I set up the printer originally with a piece of paper as a feeler gauge. Is that too close? I do have extremely poor environmental control around my printer, so that may be a factor.
Was plastic coming out of the top and bottom of the heat block because the nozzle and barrel weren't pressed firmly against each other?
The replacement nozzles I got have the same thread size, but use a M6 wrench, the original was a M8 (not sure about the exact size off hand). Would the difference in mass make a performance difference?
If I need a new heat block, would there be a performance difference between an aluminum one or a steel one?

This ended up longer than I anticipated, sorry for the wall of text. Thanks in advance for any information or suggestions.

Matt