No problem, we supposed that the word mistake was caused by the spellchecker.
We cannot say what are the best practices to setup a Sitefinity project, because this depends on the way Sitefinity is used. For example, some of the users do not need to open the site in Visual Studio.
From my point view, you have chosen the appropriate way.
As to your questions:
1. You are absolutely right here. Seems we didn't consider very well this implementation, if there are many user controls, it's difficult to organize them in the UserControls folder. Thank you for bringing this problem to our attention. We have an idea to improve this functionality, so when you upload a user control, it will be added to a sub-folder of UserControls with name, which is the same as the name of the group (in the toolbox).
When uploading a control if you define it in a group 'Test', the control will be uploaded into ~/UserControls/Test/ folder.
Do you agree with such implementation, or you meant something different?
2. Here are some tips to make the build of Sitefinity Web Site less time consuming. When you build a Web Site, it builds all files in the site, but the RadControls folder contains too many files. You can exclude the RadControls folder from the VS.NET Web Site by setting it as read-only in Windows Explorer (make only RadControls folder read-only, do not apply changes to it sub-folders). You can do the same with the Sitefinity folder. Also, you can configure the Web site to not build a s a part of the solution (Property Pages -> Build -> Uncheck 'Build Web site as part of solution').
This is the way I set up my Sitefinity project.
Hope this will help. Your Telerik points were updated for reporting the Upload UserControls issue.
the Telerik team