Charles Javier Y wrote:
Is it correct that they ask for your email to give you more information about the job or to have an interview by chat(gmail)?
No. Don't do that.
Please be careful not to share any private or sensitive information with clients on Upwork. All the information needed to hire and pay you via Upwork is available on your profile. Also, please note that any requesting of free work is not allowed on Upwork, and it is ToS violation.
re: "I have client asking me to sign up first for NDA and do 1000 research work first before they have me contract."
It is common to sign an NDA before working or even before doing an interview.
Someone asked you do research before you have a contract???
No, that is not how this works. If a client wants you to do research or any other kind of work, then they need to hire you first.