The Golden Crate

the weakest I can get the death-bot is three armed. How else can I weaken /harm it?

Use a Blast Rod. That's the only way unless you are extremely lucky with the dice rolls. Even with a Blast Rod you need a little luck to defeat it.

Which creature did you fight at the very end?

The interstellar lumberjack who looks at you through the hole in the door is able to tell immediately that you are not one of his kind, because you are lacking one very obvious physical feature that no self-respecting logger would be seen without. In tGC every one of them had this feature, you don't, so you need to go and get one.

I've worked out the secret of time travel, defeating the Death-o-saur, opening the crate and so on, but I seem unable to find Pomplompotom alive. Any hints where I should be looking?

Going back in time is important, because you need to get something. Once you have it, you need to use it at the appropriate time. On another note, you mentioned previously fighting the Death-bot, and now the Death-o-saur. You certainly make things difficult for yourself, as it's not neccesary to fight either of these opponents.

I asked previously which creature people fought at the end, but no one replied. The reason for my curiosity is that the creature you fight at the end varies according to the path you take through the book, and hence how many of the shape-shifts you can kill before they merge together into the final monster. If you kill all of them, you just fight the Merchant Prince of Projudia. If you don't kill any of them, you fight the death-o-saur. Between these two extremes are 3 other creatures.

Actually, the adventure can be successfully completed without going back in time. It is just extremely difficult since it means you have to fight the Operations Assistant armed with no more than a laserknife, and then fight the death-o-saur. But it can be done.

I fought the Tarantula-Man (well actually I emptied my blaster into it and didn't need to kill it in combat).

I finished the game to the end, but pomplopmton (that right) got killed, even after I hard effort of killing the dog-bot and the death bots :(

I assume you are reaching the ending where you are put in a cell and Pomplompotom's father kills you in a fit of grief. If so, you are missing something. You need to:
1. Retain 2 objects from eariler in the adventure
2. Open the Golden Crate before you get back to Amorphonon 12
3. Use what's inside carefully (or recklessly from another perspective)
3. Apply what you've learnt.