The use of "beyond" by itself is awkward although we get an idea of what is meant, i.e., one needs to keep going, however in English one would expect there to be something more to describe "beyond (what?)", e.g., beyond those trees, beyond the sea, beyond comprehension, beyond help, etc. Perhaps the French expression "il faut aller au-delà" is perfectly fine, but the English translation leaves one wondering. As to using "further" or "farther" would depend: "farther" is usually used in regard to distance (but not only distance) whereas "further" is generally used in a broader sense which could include distance but also making extended progress on some effort, for example. So "further" would probably be a better choice in this sentence since it is both clear and covers the various possibilities that may have been intended.
[Edit] Incidentally, Larousse gives an example: "Au-delà il y a la mer" = Further on there is the sea. http://www.larousse.com/en/dictionaries/french-english/au-del%C3%A0/150953
I would argue that "further" isn't quite the same thing as "beyond." But in any case, I think it's important that a certain awkwardness is maintained to shift the mind into French mode, so to speak, and to maintain a bi-directional consistency that doesn't mislead the student. I've tried learning from sources that give freer, more natural English translations, and I find that I have a harder time grasping French sentence structure that way.
Yes 'au-dela' works in French. 'Beyond' is the literal translation, but 'further' conveys the correct sense. It is the understanding and correct use of the sense that gives us the correct use of the language - looking at prepositions is a very good example of this where completely different ones are used in French than English to express the same sense - I am cold/ J'ai froid, I have fallen/je suis tombe. I live in Paris/j'habite a Paris. You have to change the words to make sense.
Because "il faut" is always impersonal, and is probably best translated as "It is necessary". To specify that the obligation applies to a particular person you need to follow it with the subjunctive form of the verb (which would be "aille", in this case): "Il faut qu'il aille au-dela", meaning "It is necessary that he go beyond". http://www.learnfrenchathome.com/grammaire_should_do.htm
To me personally "Il me faut" sounds a little off key, kind of like someone saying "the house of Dave" in English instead of "Dave's house". Both are entirely correct, but in most contexts "the house of Dave" just doesn't sound right. There's a pretty good discussion on that topic here: http://forum.wordreference.com/showthread.php?t=1726157 The they reach seems to be that "Il lui faut" is correct but is less idiomatic.
Any native French speakers care to enlighten us further?
You can say il me faut. http://dictionary.reverso.net/french-english/il%20me%20faut
There is a difference between "further" and "farther". "Il faut aller au-dela" (I can't do accent marks on my computer) means to go further (or beyond). What change would make it mean go farther (as in distance)? And why not plus loin here? Does plus loin mean both further and farther? By the way, most English speakers have trouble knowing which to use, further or farther.
Here's a tip for typing accents if you're using a PC with Windows: go to Control Panel, Region & Language, Keyboards & Languages, Change Keyboard. From there, you can add alternate (virtual) keyboards and switch between them on your task bar with two mouse-clicks. I use "United States International" because it keeps all the regular keys where I expect them to be but also allows à, á, ç, â, é, è, etc. There are others but none of them will do all the characters or don't have a "?" or such. Voilà ! Il marche !
“Il faut” in French is very imperative, like Raul_Duke wrote, “il faut” is impersonal, so it means an obligation, something you cannot avoid, so “should” is not strong enough. “We should go further” would be translated into “Nous devrions aller plus loin“ or “Nous devrions aller au-delà”. “It is necessary” is probably the best translation for “il faut”. Sometimes, it can be translated by “must” (though not used to translate word by word): “Il [nous] faut partir” can be understood as “We must go/leave” or “It is necessary [for us] to go/leave”.
Because "il faut" translates to "it is necessary." "It is necessary to go beyond" isn't a word for word translation. If you want to do a word for word translation using must then it would be "one must go beyond." There is no "it" in this sentence to be inserting into the word by word.
"It must go beyond" is a statement declaring that something (it) must go beyond. "It is necessary to go beyond" is a statement declaring that there is a need to go beyond.
"It is necessary to go beyond" is a sentence similar to "it is important to pay your bills". The sentence is giving you advice somewhat. The first sentence you are confusing it with is just telling a story about something that has to go beyond. Is that clearer?