Hi,
This is our Free Support Section (it is not a discussion forum area), and we are proving free support in case our customers face a problem with our VM Template/extension. Since you are asking about customizations, I am not supposed to provide you solution but here is your guide;
First of all, Don't edit any Virtuemart CORE php file. Otherwise you will lose your changes once you update your Virtuemart. But instead use CSS for any kind of stylization modification.
To delete TIP icon... Open the "Custom field"...
To change the font size, first of all install the "FireBug" plugin for Mozilla Firefox. After you install it, you will be able to investigate the element you are willing edit its style. Look at the Screenshot:
Flexible Support Team.