im using swype, very good

for the keyboard have emoji, try go keyboard / smart keyboard

Using swift key3.. Loving it. If u like to type more than swipe.. Allows u to customize ur typing speed although sometimes the predictions of words can be a put down.

read this: http://ezpert-gadgetry.blogspot.in/2012/07...bile-plans.html

Settings > Application manager

just download application from play store to clear all apps cache
example download history eraser

depends..

for example,
if an app has bugs, or keep running heavy load in the background until the phone becomes hot, then u need to kill it manually.

otherwise, normal system apps and apps that need to pull data like whatsapp or facebook, then just leave it.

games can kill.