BeechPapa

The takeoff and landing probably benefit the most. You can feel the tires thud over breaks in the concrete, the hum of the engines, the ground contact on landing, and it can even change the ambient noise in cruise, maybe even mimic pressurization changes. Whether it's worth it is subjective. I use headphones with FSX too and am perfectly happy using them except for the cable. Those headphones cover the bass frequencies well, maybe even with greater alacrity than the sub, so I don't really lose anything using them. It's not a full-body experience, but full-body bass experience gets you in trouble with neighbors. I still see a sub as being worth it though, but I'm into hifi for movies and music, so using a sub for FSX in my opinion is only one of many tangible benefits. 

TO, TO-1, or TO-2 are usually calculated with a tool like TOPCAT or onboard the real plane through an EFB or iPad. The calculations that effect required N1 for takeoff include: weight and flaps setting of the plane, length of runway, wind, temperature, barometric pressure, and dry vs. wet runway. The calculations required for this are complex, and where as the flight engineer used to make these calcs, that's become the territory of computers. CLB, CLB-1, CLB-2 are more or less fuel saving settings for climb and I haven't seen a way to calculate these with computers. I believe it may come down to different airliners' procedures for climb, and how much fuel they want to burn at climb. CLB makes the plane climb fastest at max n1, CLB-2 is the slowest climb with least n1 percent.
 
I am familiar with engine cutback because I often practice the noise abatement procedure leaving KSNA. Reduction height is the AGL height at which the engines will cut themselves back to the lower N1 you see on the cutback page. Restore is the altitude at which normal climb N1 (CLB, CLB-1, CLB-2) are resumed. At KSNA for instance, after a very steep climb at max n1 from a short field, engines must be quieted at 800ft and can only resume once the plane is high enough or far enough away from neighborhoods around the airport. By setting Reduction at 800ft, and restore at 3000ft you can effectively simulate the noise abatement procedure. EO (Engine Out) Acceleration height is the height at which the plane, if it senses an engine failure, will lower its pitch to exchange climb power for acceleration power. The reason for this is that if you had an engine failure you can't maintain the same climb rates and you need to start thinking about maintaining speed (and lift) instead of gaining altitude. For EO Accel HT you are effectively telling the FMC: if you have an engine failure at this height, all bets are off for the cutback, go to max thrust and pitch down for acceleration instead of climb.
 
Hope that helps. I really dig the FMC cutback options, they make it possible to mimic real world procedures to an exact T... or an exact N1 to be more precise.       
 
Edit: Whoops, looks like previous posters covered the same info already while I was typing. You've got plenty of info now. 

You have to use the ARPT function as shown on the EFIS to display the distances to your chosen ALTN airports. These distances will only show if they are beyond zoom range. In the above screenshot, my closest manual alternate is CYQX, but its within range, so distance is not show. For the other manually-entered ALTN airports at New York, Miami, and Quebec the distances are shown. (this is not realistic - I chose these airports because they are far away from each other, and they wouldn't clutter up the display). The other airports that show up on the ARPT page other than your manually entered alternates are airports you should be diverting to instead if the weather is good. No sense going to CYQB if CYYR will do the job.    
This is the only other way I know how to get distance info without ARPT activated on EFIS. If you select a manually entered alternate in the ALTN page, it will show its distance regardless the EFIS mode.
 
Hope that helps, you should get used to it after a few flights.