If you go 3/4 upgrade in and out of your HW tank and to fixture take offs, the volume/pressure ratio is a wash as your PRV is regulated 65-85 psi and there is usually more pressure supply from the main to offset the increased volume/pressure drop by upsizing.
If the piping in your hose is easily accessible, I would scrap as much copper as you can and replace with pex.
As far as average line in size from main to curbstop - it differs from muni to muni. Old school is 3/4 in virtually all muni's but the ones that have mandated single family dwelling fire protection upgrade minimum 1". West Van upgrades to 1 1/2" .
I did a $60 000 bathroom reno in Shaugnessy. The faucets alone were $7000 for the pair. Most suppliers have decently priced baseline fixtures in multiple finishes that can be had for a reasonable price. $500 showerheads are for people that want to waste money and tell their other rich friends about their $500 showerhead at cocktail parties.