Yes, use it the same way as in English you use "whereas"

(the same goes for all those words starting with "er" like: erom, erlangs, erin, etc.)

No, we use "er" only once. So "ernaar" gets split up into "er" and "naar" when it is separated by other words. So the construction is always: verb + ernaar OR er + verb + naar

Yeah this sentence is not very nicely written and I would definitely not use it. However, just to take away your doubt, I think the writer means to say with "uit" materials that come from deep within the earth (so under the earth's surface), and "van" in general materials that can be found on earth like wood or somehing (on or above the surface). Anyway it's still not beautifully written and you'll never see this construction again, so I wouldn't worry too much about that!!

Yes correct! If you want to refer to "he" being a teacher, besides doing/being something else, you need to invert the verb and subject and say "Ook is hij (een) docent". The second version that you wrote, "Ook hij is een docent", you use to express that "hij", just like someone else you probably just mentioned in the conversation, is a teacher.

Where did you read this sentence? Even as a Dutch person the second part to me sounds a bit strange. Could it be that you got this from a Belgian source, and that it is Flemish? Normally you would not say "die precies geen ideaal voor hen is geweest", because honestly it makes not much sense and to me even sounds wrong. Maybe someone else understands that part and can explain it.. But for what regards your question about "voor zich": "zich" reflects back to "iedere scholier", but the verb is not "zich voorhebben". Instead, it is: "voor zich hebben". This means something like: to have in front of you. So every student has had a professor in front of them/has found itself with a professor in front of the class, etc. You can use this expression in other situations too, like for example when you are on the phone with someone and you want to tell them something about a document you currently have open on your computer screen. You would say: "Ik heb hier een document voor me, en daarin staat ....". This is the first example that came up to me. Hope it's clear!

You are right, if you say "worden bereikt", it means somewhere in 2040 this goal must be reached. Instead "zijn bereikt" means that by 2040 this goal must be reached for sure, but it could also be before that. Probably they use "zijn bereikt" instead of "worden bereikt", because it is strange to set a goal 20 years in advance and know already now that 2040 will be the exact year in which the goal will be reached. Now 2040 is more like a deadline, so the final year it should be reached, but before is also possible. I think this best explains your doubt, but there is not a huge difference in any case!