After a lot of trial and error, here is the working death tower. I did a little peeking online at the way people had made them, but choose not to go with the 1:1 copy, instead I set up the floors in the tower to create a cross where the mobs drop through to the bottom, rather than holes around the perimeter. The biggest issue was that I set the collection point 24 blocks away, which where I was initially going wrong. But now I have my crafting and chests all set up 24 blocks away so that while I'm working the tower is processing, which I in turn make into TNT, 25 so far and a lot more on the way.
The tower itself took more blocks than I care to remember, I wore out two diamond shovels and a diamond pick building it and the tower itself is 21 x 21 and about 20 high, one big cube of death. =) The way it works is that on each floor there is a waterway that is 3 wide and 8 long that leads to a drop point to the floor below. Eventually they all lead to the cactus room where the mobs drop in and are either killed by the cactus where the water carries their loot down the shoot or...
They get to sit in the phone booth of death (I'm saying death a lot). In this little room any mob that hasn't been killed by the cactus (usually the case) falls in and drowns, it can look kind of funny when you have 4 in there at a time. I'm a little worried that a glitch might allow a mob to get out, but so far so good.
After they die, the loot flows down a little stream to the collection point.
After running around out in the world for a little bit, it's always a good idea to come check the spot for any loot that may have collected. The key is that as soon as the chunk with the mobs spawns, the machine goes into action so if you're walking up to the castle, it probably already has some loot waiting at the bottom.
And speaking of loot, I decided that it was time to put a vault in considering that this was going to be my new home for awhile.
I thought that it looked pretty clean.
So after all of my building I needed to cut loose a little and go out exploring and do some cave diving. I found a small cave near the pumpkin patch by the tower and went down there looking for supplies, and I really needed supplies because I was actually running out of coal, not to mention all of the diamonds that I had gone through to make the tower.
As I dove down I realized that the cave I was in linked up to a cave that had previously been explored by I'm guessing Druss. Thankfully there were still a lot of dark areas to take a look in, including a passageway that took me to a huge room down at the lava level. The best part it held 6 diamonds, well 7 but one fell in the lava as I was digging them out. So that was awesome, I was running low on diamonds so now I'm back in business.
Finally before going to bed I decided to go out exploring the countryside looking for more surface coal. I never found any coal, but I did find the mountaintop that Crash had to hide out on one night while he was exploring. I'm amazed that he made it through the night on that unsecured hill with a bunch of torches. Anyway I'm not one for roughing it, so I build a little lookout up there to keep me safe, I also added some supplies in case anyone gets lost out in the woods. If Crash wants to break it back down that's cool, but I did leave up all of the torches on the peaks so it's not really that changed up there.