The incoming gas service will be more than capable of supplying what you need, the meter may or may not need to be changed.
The other questions are best answered when you have figures, but expect the top end of your guestimate for a good one.
The break tank can be sized better when you have the demand and recovery rate figures.
Don't forget the kitchen cold should be raw water connected direct from the mains.
You may also wish to factor in a water softener if you have hard water, that would slow the recovery rate.
As we are saying you have all the ideas, what you need now is to thrash them out around a table with a couple of installers to get the best plan for you.
The other questions are best answered when you have figures, but expect the top end of your guestimate for a good one.
The break tank can be sized better when you have the demand and recovery rate figures.
Don't forget the kitchen cold should be raw water connected direct from the mains.
You may also wish to factor in a water softener if you have hard water, that would slow the recovery rate.
As we are saying you have all the ideas, what you need now is to thrash them out around a table with a couple of installers to get the best plan for you.