I googled and found the below helpful references. Currently I want to run all from the command-line (for easy of execution & quickness) in cases:
For question
5 All tests except the ones marked as category [TestCategory("some-category")]
Use
mstest.exe /testcontainer:yourTests.dll /category:"!some-category"
If you need to exclude more than one category, use
mstest.exe /testcontainer:yourTests.dll /category:"!group1&!group2"
Reference: /category filter