Hello. This is my first MMO. I use a normal keyboard and mouse (wireless.)
First, I wonder if I should buy a keyboard/mouse special for gaming or it is unnecessary.

Second, I would like to know how people use their hands. I usually move the character with the left hand (ASDW keys), and use the right hand for the keybound keys, tab between enemies and mouse.

I keybind the most frequent attacks and buffs to one key (not ctrl+key) so that I can use only one hand (if they are on the second hotbar, I search for unused keys and eliminate the ctrl+key keybind), and for the less frequently used or not urgent when needed, I use the mouse click. This way the left hand is always in place if I have to move avoiding an attack.
Spirits Within, Circle of Scorn, Hallowed Ground, Tempered Will, Flash, Provoke, normal attacks for combos, buffs (except Bloodbath and Fight or Flight), marking enemies 1 2 3, have one key keybind.
Stoneskin, Cure, Cover, Oaths, etc. have ctrl+key but I use mouse click usually.

I would appreciate suggestions or tips if you feel I can do it better, thank you in advance.

Main problem I have observed is when I have to use strafe, I change the left hand finger position, forget to return to normal position, then I don't move as I should and problems appear (main place this happens is AK at the wall, I have to grab the wasps, flash, try to stun, avoid floor attack, look to the front before I get hit back...)