Bali - Shanghai - South Korea - Tianjin - Beijing - Bali

Hello,
I am planing to stop in Shanghai en route to South Korea, then in the way back I am planing to stop in Tianjin, then go to Beijing and fly back to Bali.
1. Am I allowed to apply for 72 or 144 hours twov in Shanghai and then again in Tianjin few days after (I will spend in South Korea only 3/4 days)?
2. With 72 or 144 hours twov I can move between Tianjin and Beijing correct?
Thank you.