Okay ladies. I need opinions. My mom bought me a playtex bottles with some drop in liners to use for…

Okay ladies. I need opinions. My mom bought me a playtex bottles with some drop in liners to use for Mia, because the liners apparently help with less air bubbles and gas. I plan on breastfeeding and pumping, which is why I need bottles too. Why question is, can I heat those in a bottle warmer? And will it be too difficult to transfer the milk I pump from one bag to the other? I don't want some difficult process to go through, especially late at night