The MySQL databases are stored on the same servers, yes.
What's great about a
VPS Hosting is that you have all the control of a dedicated, i.e. you can install any version of MySQL server you like and set it up so it performs as efficiently as possible for your needs.
I'm not sure about question 3, will have to leave that to the eUK staff.
The datacentre is located in Maidenhead (
http://www.eukhost.com/uk-datacenter.php)