Contact and Motion Sensor

Hello, Currently, I have ring door bell and stick up cameras which are doing amazing. I also have motion and door sensors from Samsung Smartthings but they are not doing too well. I am thinking of getting ring motion and door (contact) sensors since I already pay for the protect plus plan but I have some questions before I make the change. 1. I simply need the door and motion sensor and not the full kit, is that possible? 2. With smartthings, there is a hub that is required, does the ring version require a hub? 3. I like to add automations that is available in smartthings, does ring offer that? Hopefully someone can help me with this.