think of it this way, I keep a ZIP of the STD folder handy in case I bork something up, when adding a ship or ships, make sure to follow the readme, and have a checklist for each ship, mine kinda goes like this :
chief.ini - 2 entries ( check ! )
ships.ini - 1 long entry ( check ! )
stationary.ini - 1 short entry ( check ! )
technics.ru - shipname entry ( check ! )
( test by heading straight for your FMB or full mission builder, add the ship onscreen and hit play to see her go )
having a checklist helps you avoid forgetting to add an entry and eliminate one of the most common mistakes in adding anything into IL2 ( a 70% CTD due to a missing ini entry ) but as stated above there might also be conflicts with other mods, "assembling" a custom mod install takes a bit of patience and testing.
I know the big E is supposed to be a yorktown class, but I needed a stand in, so I repainted your generic essex class CV9 as a "theoretical remodel" - thanks again for the excellent set of carriers to fly from (now if I can only get the CVLs to work )