I can only give you examples of how I put it all to use. Others may have their own way of doing it.
For example: My Extender chip, as received is a 98 octane chip. That is to say, it comes with a built in timing curve of 23* in 1st and 2nd gears, and drops to 21* in 3rd and 4th.
Since this is now my "do it all" chip, I set my BASE timing for street use to position E, this reduces BASE timing across the board by 4*, so in essence my car is running 19* and 17* instead of 23* and 21*.
When I go to the track, I will start out by setting the BASE timing switch to position 3. This adds 6* to the chip, so now my timing is 29* and 27*, so in essence it is now (timing wise) been converted from a steet chip to a race chip.
I seldom need to change the WOT timing switch unless track/weather conditions dictate otherwise. As an example, if I'm racing up in the high dessert in Palmdale where the DA can sometimes reach over 4,000 feet. I may need to reduce my BASE timing as much as 6*(back to 0 in my case) to help with my starting line spool up. (NEVER MESS WITH BASE MAF TO ACCOMPLISH THIS). BUT because I took 6* out of BASE I also need to put 6* back into the WOT timing to get back to where I want to be once I launch. Remember, those two switches arithmatically add to each other. In other words suppose you set BASE to +4 and WOT to +4. As soon as you go over the WOT threshold in Translator, you will be at +8(could be disasterous)(why my engine is apart right now)(don't make settings in the dark)

Another example: setting BASE timing to -6, and setting WOT timing to +6. Once over the WOT threshold in Tranlator you're timing is whatever is in the chip, or 0 change
BTW the WOT threshold I refer is generally 3200+ rpm, and 75%+ TPS (I think).
As for fueling: I first find the best MAF BASE setting to match the MAF (with a 3" maf you start in position 3 and go from there, either 3, 4 or 5)(with a 3.5" maf you start in position 0 and use either 0, 1, or 2) so that I see the best overall idle BLM numbers. This indicates a good stoiceometric A/F ratio and most everything in balance. Once I find a good BASE setting, there's really no reason to change that knob for any reason.
The important factor in fueling changes now becomes your MAF WOT switch. This is where the beauty of the Extender comes into play because you are now able to richen or lean your WOT fuel curve to suite the needs of your engine's needs. Always start in position 0 and you can either go up (rich) or down (lean) to suite the situation.
I use position E (8%lean) for the street, but at the track, since I use 114 race gas, I can afford to go leaner, sometimes going as low as position C (~16% lean).
It all depends on what your car likes. No two are the same, and never assume that someone else's setup will work in your car.
Hope that's all clear