Zork: Stumped

So, I'm stuck on Zork.  Stumped.  Bamboozled.  Stymied.  Confounded.  Snookered.  Writing synonyms for stuck because I don't really want to acknowledge how stuck I am.  This game has me buggered, and I have no idea what to do next.

That said, while I don't know what to do I have a fair idea of where I'm supposed to do it.  So, in the interests of clarifying my problems, I'm going to run through all of the things that are giving me trouble.  Perhaps writing and thinking about them will yield some answers.

• The Bank.  There are three things of interest in the bank.  One is a curtain of light that seems to be impassable.  The second is a huge stone block that seems to be some sort of magic vault.  The other is a portrait of J. Pierpont Flathead, the bank's chairman.  This portrait is one of the treasures I need to collect (I assume so, as picking it up increased my score), but an invisible force prevents me from taking it out of the bank.  ADDENDUM: I've been able to walk through the curtain by typing WALK THROUGH CURTAIN.  I emerged in a room with no exits.  A gnome appeared, then got impatient and left when I couldn't figure out what he wanted.  I wasn't able to find my way back out of this room, so it looks like I'm stuck again.
• The Entrance to Hades: There's an entrance to Hades that is blocked by spirits who won't let me pass.  I don't know what's going on here, because I know what to do: ring the bell, light the candles and read the book (all items found in the nearby temple).  I remember it from the commercial version, and I've even looked at a walkthrough (while carefully avoiding hints for other puzzles).  It has to be correct, but none of this works when I try it.  Perhaps I can't do this yet, or perhaps the version of the game I'm using is bugged.  Either way, it's seriously irking me.
• The Machine: Deep below the coal mine there's a machine that has a compartment and a switch.  I seem to remember from the commercial version of Zork that I can put a lump of coal in here and the machine will turn it into a diamond.  I have the coal, and it fits in the compartment, but I can't operate the switch.  The description makes it seem as though my fingers are too big.  I've tried eating a cake that shrinks me, but that didn't work.
• Aragain Falls: After riding an inflatable boat down the Frigid River, I dug up a statue on the beach (one of the treasures).  The trouble is that I can't get the statue back upriver, as the current is too strong.  Aragain Falls is nearby, but dropping over the edge is a fatally bad idea.  There's a barrel at the top of the falls, and I was able to ride it down the falls, but that killed me as well.  I wonder if I can put the statue inside the barrel and push it over?  (Nope, no luck there.  I can drop the statue in the barrel, but I can;t figure out a way to move the barrel.)
• The Balloon: At the bottom of a volcano there's a basket.  Attached to the basket is a large cloth bag, a braided wire, and a receptacle.  Obviously, this is a hot air balloon, but buggered if I can get the thing to launch.  I would think that I need to put something flammable in the receptacle.  I've tried a lump of coal, some timber, various pieces of paper, the torch, a match, and even a lump of bat guano.  None of these items fit inside, and I'm otherwise out of ideas.
• The Robot: This one will take some explanation.  In one of the more remote dungeon areas there's a machine with three buttons.  These buttons are electrified, and touching them kills you.  To the south of this machine there's a closet, and inside the closet is a crystal sphere.  Taking the sphere results in the activation of a deadly gas trap.  The logical answer here is to use the robot, which will follow your commands.  The robot can survive pressing the buttons, and they seem to activate a magnet or something in another room.  None of them deactivate the trap, that's for sure.  I need to explore this more, but nothing I've tried as yet has worked.

So that's where I am, stuck on six puzzles that all have me scratching my head.  I'll keep plugging away at it, and hopefully by next week I'll have made some sort of breakthrough.  I might download a different version as well, just to see if the bell/book/candle do anything at the Entrance to Hades.  Otherwise I'm not sure what I'll do.  I was enjoying this game, but now it's edging into frustrating territory.