From KL to Melacca by bus is about 2.5 hours. However take note that KL is notorious for bad traffic. And the main bus terminal in KL is in the downtown core. So one thing to take note is that you will need to factor in the travel time from the bus terminal to the airport, as it is quite a distance (probably about 1 hour by car due to traffic). Else if you go all the way to Melacca and back to KL downtown, and you need to catch a flight out on the same day from KL...you may miss your flight if you don't factor in this travel time.

Equatorial hotel in Melacca is the most central your gonna get.

Cheers!