On your first question: While TFS allows you to grab sources by Label, there is no way to setup a a workspace configuration that is bound to a specific Label or Changeset for a specific path. The only thing I can think of would be to create a batch file which fetches the latest version:
tf get $/Project/Sources /Version:T /recusive
tf get $/Project/ComponentA /version:LMyLabelName1 /recursive
tf get $/Project/ComponentB /version:LMyLabelName2 /recursive
The way forward to do this is to publish your external references to a NuGet repository (can be your own) and then configure NuGet to get a specific version. A CI build can publish a new version to your NuGet server. And you can setup your own server so that you don't need to publish all your binaries to a public server.
On your second question: yes you can build by label in the Queue Build screen you can setup the version to build which will be built:
You can specify a Changeset number (C######
), Label (LLabelname
) etc. Any version spec will do (see the commandline docs for a explanation on version specs).
By default, no easy referencable name is generated if you build by label. I suspect that some clever build customization will allow you to drop the build output in a predefined folder based on the label name, but there is no such out-of-the-box functionality.