brushless losi 8b

right i have had enough with the temperature of the motor
it is getting too hot for me and the runtimes aren't up to much either
if i was to go for the 2650kv MMM combo would i see quite a big increase in runtime?
also is it ok to run the mamba monster combo on 4s 4000mah 25C lipos like these:
http://cgi.ebay.co.uk/RC-Helicopter-...1%7C240%3A1318
or would i need a battery that could deliver more Amps?
if i was to keep my mamba max and just buy a motor would the temperature of the esc go down because i have gone from a 9xl motor to a more efficient motor?
will 4s be plenty on a 2000kv motor or would i just need to gear it up a bit?

thanks richard