Javascript to gather visitor information

General information for the website: n/a
Description of requirements/features: Hi

I need some JS written so i can track visitors on my clients sites. The info i need is the following and data would need to end up in a mySQL database on my server (different server to clients). The code would need to be added to my clients site ideally in the footer.

The page they are on.
An individual unique ID for every visitor.
The date and time.
Visitor location (country and county).
If possible if they have been on the site before (a previous day).
Would need to know if the visitor is a robot or human.
When they leave the site i would need to know the date and time of that and if possible what site they went to.
Screen resolution of the visitor and if possible the device they are using (ie: tablet, phone).
Operating system of the visitor.


This info would need to get to my database very quickly (within seconds) and the code would need to be as small as possible.

Any questions please just ask.

Stuart
Extra notes: