Yes, English often uses the present tense with future meaning in subordinate clauses, where Latin uses the future tense.It looks like poterō is the future tense of possum, so I wanted to show that; but I suppose the "as long as" does that already.
English has two kinds of infinitive. The one with "to" and the one without "to". After "can", you use the one without "to". That's the way it is. Just a peculiarity of English that isn't shared by Latin. Nothing to worry about; the translation still corresponds.Second, imperāre is an infinitive, but "to control" sounds wrong.
You can translate it with "over" if you like, but it is dative. That's the case used with impero to denote the person or thing one is giving commands to.Last, cupiditātibus was noted as dative plural in my commentary; but I think it might fit better as an ablative plural with the preposition "over".
Sometimes, Latin will use a bare ablative where English would use a preposition. It isn't the case here, though.(If a noun is in the ablative, is it okay to supply a preposition that isn't already there?)
Yes, it's important to understand the structure of the original first.I find that there is a strong temptation, for me, to move too quickly to the idiomatic before fully grasping the meaning of the text. I do this because I don't fully understand the sentence. When translation is done the right way, one gets a literal translation first; and then polishes it with idiom.