i'm assuming you're using 1.4x judging from the screenshots i saw?
for your first question, i believe there may be a plugin for that you can use. i'm not exactly sure what you're looking for, but one of these might help you: http://www.glorioustrainwrecks.com/node/5462 . if you can show me your code, i might be able to help you better? alternatively, if you want an option to take you to some flavortext, then be removed when the player goes back to the same area, what i usually do is:
<<if $cats is true>><<else>>i really like [[cats]].<<endif>>
then on the cats page:
i have a cat named chocolate. <<set $cats = true>>
i can't remember my syntax so i think i made a mistake... but this should work.
also, for the layered images, it's completely possible! you don't need plugins for it. o: i can't remember now to do it specifically right now, but i had a little demo with exactly that, and i believe i used variables to change the images. i'll open up my project and take a look asap!
your last question stumps me a little. i don't remember using those in twee? can you send me an example of where it's used