One option for modifying the CSS that's loaded, is, like I mentioned before by using a custom theme for Sitefinity, you can actually check this tutorial
, I believe it might make it easier to introduce you to the concept. Another option is to simply drop a CSS widget on your page/template and write your custom CSS there (the CSS widget is located again in the widgets toolbox on your page/template under the Scripts and Styles section. For testing purposes you can add the following CSS:
Please note you need to publish the page for the CSS to apply. More information on the widget can be found here
Now on the second question related to VS - using the edit in Visual Studio option gives you the option of adding your own web user controls, application modules, masterpage templates which you can use in Sitefinity, as well as modify the existing configuration files. You can take a look at the tutorials section
from our Documentation, I believe you will find it useful.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items