1.For thousand sons you need the chaos index, and chapter approved. The units you can take are explained in the index.
2. No. These are CSM only relics- thousand sons are getting a different codex with relics, warlord traits etc. In 2018.
For how to use them: what do you have? It's pretty straight forward in that, to start with you should just walk up the board and shoot out the infantry trying not to let yourself get charged.