What are the prerequisites (things that are needed) for salvage?

Hull Scraping - Damage Tech (I believe this has been completed a long time ago), and partial persistence, to allow for ships to spawn correctly.
Component Retrieval - Physicalised ship components and systems are needed, so that you can retrieve them from the ships. Power systems and pipes also need to be working the way they want them to (look at the resource generation and item control section for more info).
Maw - They need to figure out exactly how ships will be broken down and crunched up. Probably the most complicated salvage mechanic to implement.
Siphoning - The room system needs to be working correctly, so things can be pulled in/out of rooms (e.g. Oxygen). Life support also needs to be working the way they want to. There will need to be entry points in fuel tanks to allow for fuel to be pulled out of them.