TK,
I would not plan on swapping out the panel with the conductors live. There has to be a Service Disconnect somewhere. With all the junk Verizon hung on the wall adjacent to the meter, I just did not see it.
If I have to, I'll get the POCO to show me the disconnect switch.
TK, - My thinking on the use of the 200 amp panel is to have the new panel in place in case we ever decide to go to 200 amp service.
Right now, If I go with a full rated service amperage of 150 amps, I do not have to change the service entry conductors. By the way, all three conductors are 2/0 AL. Nor will I have to change the ground rod. I believe that the panel is grounded to the cold water pipe that feeds the hot water heater about 15 feet from the panel.
I got to do some more discovery work and get the permit before I actually start the work.