My official job title is college student. On the side I am a part time photographer, and run a small metal and composite fabrication shop mostly working on high performance cars.
The 3/16ths diameter stainless does not have the same restriction per foot as 3/16ths beer tubing. Try a slightly longer beer line. Although with 5 feet of beer line you should still have plenty of restriction for serving at 12 psi. I have never needed lines longer than 6 feet and don't...
Welcome to our corner of the web. Best tip that I can offer is to read as much as you can and feel free to ask questions here. Lots of great brewers who are willing to share their knowledge.
I use both the BCS and an Auber PID. It did take me a while to really figure out the BCS. Keep reading the wiki and check out the forum on the BCS site. Using it to control my keezer and fermentation chamber has been one of the best things I have done. Built in data logging!
Are you switching to the standalone PID for ease of use without a computer? The BCS has four PID outputs and is a very powerful control device to have in a home brewery.
Please provide a link to the mentioned cast iron head for a pump. I have never seen one. The black pump heads are Polysulfone. http://www.marchpump.com/809-pl/
Magnetic drive impeller pumps are lubricated by the fluid that they are pumping. Running the pump while dry for extended periods of time will cause damage to the impeller or the shaft. The pumps are not capable of pumping air and will always leave a bit of liquid in the lines.
I suggest that you do some Google research on home circuit wiring and Ohm's law. You can plug as many devices into a power strip as you want as long as you do not exceed the rated capacity of the circuit. Ohm's law is your friend and will answer questions 2 and 3. In regards to #4, my 5500...
I have always looked at the purchase of a cylinder (CO2, O2, Argon, .etc) as the entry fee to the club. Once you buy a tank just swap it out and never worry about hydro testing or waiting again.