From your post, it would seem that all you really need to do is turn off your gas supply at the meter and tap into that capped off connection for the old dryer. Start by installing a shut off valve at that point. Then, you could work on the extensions at your leisure and not be without gas for the rest of the house. Check your local building codes. While there are many new materials being used for gas lines, I would be surprised if plain old black pipe wasn't still standard. If, as you wrote, you are good with plumbing, you should have no problems with a gas line. Black pipe is installed using the exact same tools as galvanized pipe, just don't use galvanized for gas. Suggestion: make a carefully measured schematic of the line, then visit your local home center. You will find all of the parts and supplies you need to put it all together. Once it's all connected and you have an outlet and another shut off in the GH, ready for the feed line to the heater, shut the GH valve, open the one at the old dryer point and test every new connection with liquid soap. Dishwashing detergent works well. It flows easily, is thick enough to coat the connections, but light enough not to clog and hide any small leaks. Natural gas is delivered under very low pressure, so the soap will bubble to reveal any leaks long before enough gas escapes to even smell it. Once you are done, have your nat. gas supplier inspect your lines. Many gas co's. don't even charge for the service.

On the other hand... I guess the pipe dope could be the cause of the blockage. If I remember correctly, the pressure of the gas in the pipe is actually very low...less than the pressure created when blowing bubbles through a straw in a glass of milk. If there is a blockage of pipe dope, the gas pressure likely is too low to clear the blockage.

I've been talking to the natural gas company to find out if my existing gas meter is large enough to deal with everything I have planned for it and the response was that it needs to be upgraded. However, they want to charge me $1325 to upgrade the meter. Major OUCH! I asked what the BTUs are for the existing meter so I could gauge how much of what I have it supports and the response I got was 300,000 CFH. I did some Googling of converting CFH to BTUs and didn't understand the responses. Anyone know how to convert the 300,000 CFH figure the gas company gave me to see how many BTUs it will cover (from my list of BTUs above)? If I have to shell out $1325 to the gas company I'd guess switching the electric water heater to tankless is a "no go" based on way too expensive with tacking on the meter upgrade, just would make more sense to keep an electric water heater, I don't like it but it's hard to justify massive amounts of $$ to go tankless. But if my meter is close enough (the reality is only two people live in the house, all of the above things would not be running simultaneous) then perhaps it is a go and I skip the gas meter upgrade.0 Thanks!

In this area, all piping before and to the meter is done by the gas supplier. As far as I know, they use 10 PSI to the meter in this area. After the meter and regulator, the PSI is about 1/2. Some gas companies use higher pressures than 10. As you have discovered, pressure is one of the important factors in calculating the size of gas piping.