UK - US flight and US internal flights

As an internet-travel-booking-novice I would appreciate some suggestions on
how to go about booking both UK - US return flight and internal US flights.

Early December, four of us need to travel to New York, on to Tampa, then
North Carolina and maybe Buffalo before returning via New York after 10 - 14
days.

Is it best doing it all with the same airline? Any carrier recommended? Or
should I let some agent (eg: Airline Network?) take the strain and do it
for me?

Similarly, any tips on booking (3*?) hotels at these places please?

I guess this all sounds elementary to seasoned keyboard travellers, but we
all have to start somewhere........!

Thanks
B