what would it take to swap in a b18b to my em1?

would i need the ecm?

if it is obd2 can i use my exsiting wiring harness?

would my gas mileage suffer alot if i use the b16 tranny? (drive 400 miles a week)

what would i need to do to eliminate the vtec? (may go lsv later)

anything else i might have missed please advise...