Translation:The book is expensive because it is old.
No, there is not difference in meaning, Het boek is duur, want het is oud. means exactly the same thing.
Is subject-verb conjugation important when using 'want' as opposed to 'omdat'?
When using want it's a main clause, so the standard word order is used, when using omdat it is reversed because it's a subclause. See points 4 and 5 here.
- Het boek is duur, want het is oud.
- Het boek is duur, omdat het oud is.
You can find more on word order in main and sub clauses here. (Take care it is an extensive explanation.)
I might have thought that "coordinating" and "subordinating" conjunctions imply different things about causation?
Nope, it has nothing to do with causation. Coordinating conjunctions (nevenschikkende voegwoorden) link two main clauses. Dutch coordinating conjunctions are: en, maar, want, dus, of and doch (not a common one). All other ones (including of) are subordinating (onderschikkend), these link a main clause to a sub clause.
Of iscan be either a coordinating or a subordinating conjunction.
So, omdat and want are interchangeable words. When do we use "komt doordat"?
What is the difference between 'omdat' and 'doordat?'
I've heard that doordat is used when the clause is out of your control, but if that's the case, then why is omdat used here?
Omdat can be used both to talk about an 'external' cause (something that is beyond our control) and an 'internal' cause (something that we could modify/influence).
Audio of the sentence is off: the word "oud" sounds correct when it is heard separately, but in the sentence is sounds like EN "oat" or NL "oot"
I typed omdat while interpreting the other way and I was marked incorrect...claiming it should have been want...what gives?
Maybe you forgot to put the verb at the end. You have to do that when you use 'omdat' but not when you use 'want' '...want het is oud'='...omdat het oud is'
I keep getting any sentence with dare wrong because your app is spelling dear incorrectly. Please note "dear" has another meaning. Dare is the correct spelling. Please amend