help! can go mouse-less or not?

help! i’m starting to feel numbness on my wrist and finger due to holding on to the mouse for a long time.

you see, at work, i’m on computer almost all the 8 hrs, then come back home, again i’m on computer for about 5 hrs. and the way my computer (both office and home) are placed, when i hold the mouse, my hands cannot stretch out fully. it has to be bent at the wrist. this cause the muscle at wrist to tense up, hence the numbness i think.
pic from injury treatment

now, i had feel this ‘wrist ache’ before one time or another but just recently my fingers too started too feel the ache – the index finger where i uses it to left click. so sometimes i have to switch to the middle finger, which i’m not quite used to.

now, can anybody tell me (or show me where) how to use the keyboard in place of the mouse? functions like clicking the ‘x’ to close a window, jump from one tab to another (on system tray or within browser), to move from one window to another (like in words), highlighting a word or several words, and so on. to scroll up or down, i know is to use the arrows keys but the thing is before i can use the arrow keys, i have to use the mouse to click on where i want to scroll, before i can use the keyboard keys.

and what are the excersie to ease the muscle tension in the wrist/fingers? i try to swing my wrist madly… and it does feel a bit better. oh god, i hope i won’t develop carpal tunnel syndrome.