So I felt like noting this all down because I see people still asking and also so I can remember because I've forgotten a couple of them at times.

First, magnet in the cargo bay is functional but malfunctions and stops working if you load a save.

To enter bridge without Noclip: When looking at the bridge, there's a ladder on the right. Climb it and open the vent to find another ladder. Climb that to get up to another vent that opens onto the bridge. From there you can disable the bridge lockdown.

Bridge: On the bridge to one side, there's a couple screens with 2 blocks of unreadable text each. For one screen the blocks control lights and lockdown, and on the other screen the 2 blocks fire the escape pods. The escape pods can only be activated from there during a reactor meltdown, essentially requiring a person to stay behind in RP. Typically this would be the captain (someone who would be content to go down with their ship) or someone unable to leave and is good as dead anyway.

The Box with buttons: This is the box you can spawn by pressing the button in the room under the bridge. The left-side button on it aims the ship's big cannon on the bottom/front. The right button makes the cannon fire at the box. The best thing I've found to do is to use teh context menu, right-click and choose drive to move the thing through the wall if you want to aim the cannon quick and on the fly.

To trigger meltdown: The two switches to the sides in the engine room open part of the third, central switch. Flip the 3rd switch to open the core vents. Get an explosive into the vent, either grenade or rocket, and it will trigger meltdown.

Escape Pods: The escape pods automatically open during meltdown during with they can only be fired after an on-screen queue and have to be activated from the bridge, essentially requiring someone to stay behind(thus leading to sacrifices or death-defying runs to one of the airlocks for an escape). Once the escape pods are activated, the passenger seated at the front of the pod can control the pod using WASD and Mouse1 to move the pod forward. Mouse2 maybe acts as a break but I'm not 100% on it.

Fire Cannon: Underneath the bridge is a sort of war room. There's a platform with a button that when you push it spawns a metal box. This is the main cannon's aiming beacon. Move this to where you want and the cannon on the front of the ship will follow it with its aim. Push the button on the box to fire the cannon. I'm not aware of a remote way to fire the cannon.

The button at the end of the engine room apparently resets the meltdown and allows it to be repeated.

If there's anything I missed, feel free to say below.