Yes. Many mixed backyard flocks include bantams, large fowl, and their intermediate-sized progeny. This shows that size can change in just a generation, although a stable new variety takes more time and care to produce.
Choose the large parent to match the desired characteristics of the bantams breed you want to size up in as many ways as possible. That will bring in fewer unwanted characteristics to breed out later.
Yes you can.
I've found a problem or two though.
Bantams tend to be more flighty than average dual purpose breeds and while I get larger chickens they still want to roost in the trees.
I've also found that the bantam tribes are not very welcoming of this mix and the mixes tend to make new tribes.