Your link isn't working for me (I think it's dependent on posts per page) but I'm going to comb through that thread and find a post that does a good job of the discussion.
As far as timing goes, just practice a lot. The best thing to do is to go into training mode with the CPU set to Donkey Kong and practice the following in order:
1. Chaingrabbing with normal dash grabs.
2. Chaingrabbing with shield-canceled grabs.
3. Walking chaingrab.
4. Standing infinite.
Once you get the timing down for each, go through and practice it all again, then test it on a human opponent. Good opponents to practice the practical application of this against are Marth, Luigi, and anyone with a fast jab (Lucas, etc.) since you'll know if you're not doing it right. I would also suggest you practice dthrow techchasing with someone you can't cg like MK, Pikachu, or G&W since it's a useful skill to have.
As far as levels go, DreamLandWorks has a pretty good guide on them that for the most part I agree with (There are a few little things I'd change, such as Delfino being a 4 instead of a 5, but otherwise it's great). Obviously the stage depends on your opponent, specifically if you can chaingrab them or not. Characters you can chaingrab you can pretty much just make them your ***** and take them to whatever their worst stage is. If you don't know what their worst stage is, you can always take them to a stage with walls (Pokemon Stadium 1), walkoffs (Castle Seige), or both (Delfino Plaza, though I wouldn't take any characters who do well on Battlefield here since half the time it's basically set up like that). Green Greens is a stage that is deceptively good. A lot of people thing that because of all the walls it must be good for chaingrabbing, but the problem with it is that Wispy Woods can often **** up the chaingrabbing with his wind. lain lost a match to Ally because of this.
As far as neutrals go, you probably want to avoid stages with lots of angles on them like Yoshi's Island and Lylat Cruise, especially if you don't have the cg down that well. Like I said, Pokemon Stadium, Castle Seige, and Delfino are the best if they're legal, but the best of his "true neutrals" are Smashville and Final Destination since they have no platforms for the opponent to hide on and a lot of space to chaingrab. Battlefield is so-so, it can be relatively unthreatening or extremely bad depending on who you're facing. Halberd is also a great stage for Dedede and I'll talk about it more below.
Against characters you can't chaingrab, you need to ensure you still get your kills fast. Because Dedede kills off the top, choosing a stage with a low ceiling is important. This is why Halberd is so good for Dedede since the low ceiling negates the fact that there's a big platform for the opponent to potentially juggle you on. Likewise, you want to avoid stages with large ceilings like Jungle Japes.
As far as bad stages go, a lot of people are saying that Pirate Ship is the worst, but I don't really think it's any worse than your average bad stage (though you shouldn't take people there). In my opinion, Norfair is the worst stage for Dedede there is (unless you're playing Ice Climbers, see below) since it's so easy to get your grabs broken by lava, it's so easy to be juggled on platforms by your opponent, and it's so hard to gimp anyone with half a brain due to all the ledges. Avoid this stage and all stages like it.
Obviously there are some specific characters who you should know about:
Never take Metaknight or Olimar to Luigi's Mansion.
Never take Falco to Japes or Final.
Never take Game & Watch to Rainbow Cruise.
Always take Wario to FD, Smashville, or a similar stage.
Never take Diddy to Final.
Always take Kirby to Rainbow Cruise (it sounds weird, but if you try it you'll find that it really does work).
Never take Ice Climbers anywhere besides Norfair, Brinstar, or Rainbow Cruise (Battlefield as a last resort but some Ice Climbers are fine with this stage). YOU MUST NOT GET GRABBED.
Never take Ike or Ganon to Pirate Ship (though it shouldn't really matter since you destroy them anyway).
As far as setting up utilt, try using it like a punishing move - wait until they make the mistake of being above you above 100% and punish them by taking a stock. A good way to get them above you is to fthrow or bthrow them and wait for them to recover high. I can't tell you how often I do this.
It's also important for you to realize that Dedede has more kill options than utilt. There's the Buuman Trap obviously, but besides that dsmash is a very good kill move. It has more horizontal range than utilt and kills at a slightly higher percent. Dash attack and fsmash are risky because they're so slow, but they both kill well under 100% and can be good ways to get a kill if your opponent trips or doesn't tech a dthrow or something. Don't get predictable with it though. Usmash is only worth mentioning because you can do it out of a dash. Otherwise it sucks. You can gimp a decent amount of the cast, so practice doing bairs into fairs.
There's also the famous Dededecide which is a nice surprise that only works once every few matches. Learning when to use the Dededecide is important since I often see a lot of n00b Dededes doing it incorrectly and failing horribly. There are a few basic rules for the Dededecide that everyone should observe:
1. Never use it on the stage. Always use it while falling close to the stage while your opponent is close to the ledge.
2. Always fastfall it.
3. Only use it when you are ahead or tied on stock.
4. If you miss, make sure you let go of Inhale fast enough to recover. Or else you will die.
Often the threat of a Dededecide is enough to make people stop playing near the edge of the stage, so feel free to throw out an inhale once in a while when you're falling near the stage. Just make sure you space it so that you don't get hit by a Marth tippered fsmash or a zair or a Warlock Punch or something.
Here is my flowchart:
http://img10.imageshack.us/img10/3739/kingdededeflowchart.jpg
Hope that helped.