Can voip user be located by a phone number? Can the voip use the phone like a regular cell phone?

Nope not a realistic proposition.
The only sort of phone user that can be reliably located are landlines.
Remember what VoIP stands for, so as long as there's a DATA connection they're good to go.
Many cell networks route voice over data in this way already.

It is not an easy task or one that can be done by the avrage computer user but it is done by law enforcement and other three letter agencies on a daily basus. If you want to hide behind woip and something illeagal you can get cought if you are the victom of something bad over voip report it.