Electromagnetic force in the fourth spatial dimension?

Purely from a non-mathematical perspective, could some/any/every-body answer my questions on the electromagnetic force in extra dimensions?

άλφα) I am curious about how in the old Kaluza theory of the electromagnetic force the equation, which he found from his equations worked when it occupied the fourth spatial dimension, encountered problems and was not a perfect answer, ie. why although it initially worked Einstein and Kaluza etc. found that it was ultimately not correct!

βήτα) How Klein's theory changed the non-workable Kaluza theory to work.

γάμμα) How this Kaluza-Klein theory encountered it's own flaws?
I think the Kaluza Klein theory as a whole worked because Klein introduced the geometrical shapes within the tiny dimensions, but could somebody please clarify.

δέλτα) In string theory, does the electromagnetic force occupy many dimensions or just the fourth spatial dimension?

έψιλον) And What is the significance of each dimension?
Does each dimension occupy a specific size in which the string has a certain amount of space in which to vibrate in? i.e. a limit on the energy it can release. Par example, the sixth dimension has enough space to vibrate X amount of energy and this results in quarks, or mabye up quarks and charm quarks, but the 8th dimension has Y space to vibrate resulting in the strange and bottom quark.

Thanks so much for any help, if possible answer each seperately if you can give me a few minutes of your time