Need ideas for transmission and slow pick up on stopn.

Bought 2002 Landrover Freelander couple months ago, Has 130000 miles on it. Plan to change Transmission fluid but no idea what kind of fluld and how many should I buy and used?
Dealer won't share ideas for been calling never return the call.
Also I noted when I slow down to stop signs or lights the start up slow to pick up. Why?
No idea if badly needed to change fluid & filter or it's the sigh of bad transmission?
Please Help. Thanks !