Looking to get my first A8, lots of questions, somewhat bewildered!

I've always wanted an Atari 8-bit, and now I've decided to finally bite the bullet and get one. And after reading through the forums and other places online, my head hurts!

In any case, I've tried to mentally categorize where my confusions lie so I can be more organized in asking them!


PART 1: Models

• I know that there is debate about which particular model has the best video out, or keyboard, or whatever else. Mostly what I'm seeing is that the 800XL is a sort of de facto standard. However, from what I can tell on wikipedia, the XE series is "more advanced."  Aesthetics, picture quality, and keyboard notwithstanding, which model has the "best" specs?
  
  
• On that same not, wikipedia is extremely ambiguous and makes it sound like the XE series cartridge slot and XL series are incompatible (not sure if this means physically, electrically, or both), is that true?
  
  
• The 800 apparently had expansion slots, were these ever used for anything worthwhile?

I'm stuck between the 800XL and the 130XE in this regard.  Moving on somewhat, as I read more and more, I found an almost dizzying array of mods and upgrades!


PART 2: Upgrades

• I know that the VBXE is supposed to enhance the graphical prowess of the A8s, and it also mentions having some sort of RGB output. Is this RGB a la SCART (obviously sans the connector)? Is this something that only applies to software specifically written for the VBXE, or does it give everything on the A8 RGB out?
  
• If so, does that then obviate the need for an S-video mod?
  
  
• Would the RGB out for the VBXE work with my Sony Trinitron professional RGB monitor? (I'm not sure what the technical name of it is, but I like it a whole lot!)  
  
  
• If not, what is the best s-video mod in terms of subjective quality of the picture?
  
  
• Is the "Ultimate 1MB" the preferred RAM upgrade? I see other ones mentioned, do these serve complimentary roles, or is the U1MB the only upgrade I need in this department?
  
  
• I've also seen several references to stereo mods employing an extra POKEY chip, are there different versions of this, and if so, which one is best?
  
  
• Are there any CPU accelerators, and if so which is the most powerful?
  
  
• What is the 32-in-1 OS mod, or whatever one might call it, and is it worth having? Are the OSes for A8 in that you boot them from a floppy like with an Apple II, or are they embedded in the ROM like TOS for the Atari STs?
  
  
• What is the Multi I/O? It seems to be rather rare, are there any clones? Is it worth having?

PART 3: Peripherals

• From what I can tell, the SIO2SD and Nuxx SDrive seem to accomplish similiar goals. Am I correct in this assumption? If so, which is better? If not, how do they differ?
  
  
• What is the best of the CF/IDE adapters? From what I can tell, the consensus seems to be that SIDE2 is the best.
  
  
• I've seem a couple of different references to methods of getting A8s connected to the Internet, or networked. The first is an ethernet cartridge. (I think this comes with Contiki built in?) The other is a Lantronix serial port to ethernet converter. Are these more or less equivalent in their capabilities or do they have different applications?
  
  
• I've noticed several people mentioning that they have 9600 baud modems. What can those be used for these days? Are they only kept for posterity and/or nostalgia?

PART 4: Miscellaneous

• I'm somewhat confused about the nature of cartridges. Can all cartridge software be run from the SIO2SD? What about floppy software via cartridge? Is this why both SIDE2 and SIO2SD exist?
  
  
• Are there any cool upgrades, accessories, or peripherals that I am not aware of or haven't mentioned?

Wow! That was a lot of text! Well anyway, thanks so much for reading!