You know the old saying: "If you have to ask..."! If you're asking this question, you should probably be calling an electrician. The answer to your question depends upon what you are trying to power up. This will determine what size wire you will need and therefore, the size of the circuit needed.
you don't run a new 120 line
You will have to install a double pole breaker in the fuse panel and then run new wire (10/3) to the location of the dryer and install the proper plug. You will need a 4 prong plug; the older 3 wire plugs no longer meet code for new work.
the voltage between 1 line & phase =120v The voltage between 2 line =240
Not a plumber however I do know it varies buy region. You need to know the depth of the freeze line in your area. That will determine the depth to install your hydrant.
You can get a ground adaptor, but it is much safer to have an electrician install a properly grounded outlet. This may require having to install a new line directly to your electrical panel.
Because they are "in-phase". In order to get 240v, you need two 120v Alternating Current lines that are 180° out of phase, that is, opposite phases. Only when one line is +120v and the other -120v will you see 240v between the wires.
disconnect the fuel lines, supply and return, and vapor line and disconnect electrical connector and drop the gas tank. Drain it first.
If the motor is designed for 120V or 220V whatever the case, it will function properly.If it is a 12V motor and you supply 120V it will make a mess and you will probably get hurt from flying debris!
You can't.
Should be ok provided you do not draw too much current.
You can install the 110v line on one stud and the coax jack on any other, just don't put them on the same stud. This will cause major crosstalk in the coax line.
If you don't know that, should you really be doing this potentially dangerous job.