Help Automating Facebook

Hey fam!
Wanted to see if anyone had any insights as to how I could automate Facebook postings. Essentially what I want to develop/create is the following:

• Post something for sale
• Auto post to massive amounts of local groups (would i need more than one account to post so as not to get banned?)
• Update posts if original post gets updated ( For example if the item is sold, update only on the main post and have it auto update on all the others)
• BONUS if item is sold, auto message people who interact and let them know current item is sold but they could come by to see new inventory.

If there is a service that already exists, i would love to learn about it.
Any and all help would be appreciated.

Thank you in advance!