It depends on the subject.
For he/she/it or a singular noun subject use wants. eg
She wants my car. The dog is hungry it wants my lunch. The man wants some money.
For all other subjects use want. eg
They want your car. The dogs want my lunch. The men want some money.
you use which when you want to ask a question like (which one do you want?) and what when you want to ask a question like (whats your name) :p
Maybe some people just like to use them or they could have a reason to why they want to use it.
Do what you want.
Use e.g. when you want to cite an example. For e.g.:(like this.) ----
If you are in an atmosphere with a gravitaional pull then you will want to use a balance, if not (like if you were in a place with no gravity) then you want to use a centrifuge.
Paper and Ballpen
when you sing you want to use your stomach and you want to open your soft pallet like when you want to yawn that is when you open your soft pallet.
when you want to know something like this :)
you dont necesaarily need to use the bathroom, you might want to or feel like you want to basicalyy people go to the bathroom alot not to use it but to change it
Use it when he/she and you ARE in an argument, and you feel like you are going to cry, or when you don't want to talk about it.
becasue they most likely want to use the phone like call\text
When you enjoy doing something or something is pleasurable to you. such as "I like to dance" or if you want to do something such as "I would like to eat" :)