The first pattern buffer on this level may be had by going into the right-hand hallway in the first large room, and sticking to the left-hand wall. This also leads to a shield generator. This should be your first stop, as you don't want to do the platforms in "Colony Ship..." again, do you???
You say you've looked *everywhere* on this level and can't find a way out? Then return to the room with 2 columns and the shield gen. On the back side of the left column is an elevator that will take you to the 'upper' portion of the lever. There is a thin ledge on this column, so the best way to get down there is to run off the ledge, directly into the side of the column that faces you. Then, *walk* around to the other side. If you fall off you can always grenade yourself back up.
To get the alien energy converter (that 'thing' in the lava), you first need to go up to the top level as described above. When you get to the room that has the one pillar in the lava and a save terminal, look around on the upper level and you'll find a button. Pressing the button will cause the pillar to drop and will allow you to grab the device. However, to get out of the lava you either need to grenade jump or wait for the pillar to start to rise again. Watch that you don't get squished by the pillar! As an option, you can immediately save the game after activating the pillar, so that you don't have to transverse most of the level again. Yet another option is to enter the lava by the 'other' passage, while the column is descending, and with this route, you can reduce the amount of manuevering you have to do in the lava. Note that you will need to 'create' this other passage by hitting the switch beforehand.
To get past the door in the 3-column room with the biohazard sign, you need to find a switch. In that same room, there is a passage that you can jump to from the middle column. This will lead you to a small battle, but to another area to explore. Within this area, either look for a secret door, or look for a gap that you can jump that is very small. Within this other area, you'll find the right switch.
There is a secret ammo room that can be gotten from the above. Move a bit into the corner of the passage, and start looking for secret doors. This stash should contain rockets and napalm canisters amongst other ammo types.
There is a flame thrower in one of the last rooms, in the room with the L-shaped platform in the lava. There are two 'rivers' of lava leaving the room. Run through either side, pick up the napalm unit on your way through, and grenade jump back onto the platform.