The power company can provide you peak demand on your current home. Based on that you can determine if a separate feed to the shop is required or can you put in a breaker such as a 100amp to your shop as a sub panel. If you have to run a separate feed to the shop do 200amp. The cost difference between 200 and 100 is not enough to go just 100amp. I did not read all the discussion but most service entrance cable is aluminum. Also it is not uncommon to use aluminum for high ampacity circuits like 50 or 60 amps. You need correct terminals and a special anti corrosion paste on the terminals. The receptacles and panel lugs will be marked AL for use with aluminum. I have three 200amp panels all connected to a single meter. They use current transformers on each panel feed and the meter totals the usage.
