For your second tooth in which the decay hasn't reached the pulp, and since u have no pain or sensitivity from it, u can go ahead with the filling. Cap not required unless the tooth structure is broken badly..
Next Steps
Get the filling immediately. Don't delay your treatment anymore , if the cavity progresses further, then u will not have the option of filling!!
Health Tips
Avoid having too hot or too cold for few days. Brush twice and maintain your oral hygiene!