Is 94 cubic feet/hour of natural gas a heavy load

Your 2# regulator is likely dropping the pressure down to about 1/4 psi which is what most appliances need. By putting the tee after the regulator and running a 80ft line isn't going to be sufficient. Longer runs generally need larger piping. Your 1/2in line wont be able to keep up. You probably should have ran the 2psi line (i.e. a tee before the regulator) and installed a 2nd regulator up there.

Here in the United States, most houses are fed 1/4psi after the meter and if there is problems with piping or a need for large appliances, generally pressure can be increased to 2PSI. Since you have 1/2" gas piping, that might explain why you have 2 PSI of gas. On my house, the line coming in is 1-1/4".

Yes you can (and fortunately for you, there is a union right there to make your work easier.)

Replacing the this joint is easy enough, but remember you are working with gas. Professionals are recommended and required in some places, as are permits.

I would use a T directly on the main pipe into the wall, a short nipple to the lower main from the ground, and whatever reducer you need for the grill line with a shutoff valve. Depending on your grill and local pressure, you many also need a regulator for the grill itself.

If you do all this yourself, remember to use the gas rated tape or dope for joints, and use soapy water, gas line tester, or use a static pressure test (Check the meter, then shut off as much as possible inside the house and turn on the main between the meter & your work. After 15-30 minutes, the meter should not have changed. If it does you have a leak.)