Here’s my two cents worth:
As Mosteque and Dead at Heart (what a name!) and especially Alan mentioned, of course you can end a sentence with a preposition! Native speakers do this all the time. Even in written English. It’s quite normal. The Churchill example that Alan mentioned is also well-known in the U.S. and it’s always been a favorite of mine. I just love it! It’s so exquisitely bad that it’s hilarious — even though it’s grammatically correct. Churchill’s sentence sounds ridiculous and absurd because it’s so completely unnatural — which was precisely Churchill’s point. winstonchurchill.org/i4a/pag … id=388#put
Also, the word ‘whom’ is dying in English. In reality, it’s rarely used nowadays except in extremely formal English (emphasis on extremely!). For example, in the sentence “Who are you talking to?”, the word ‘who’ is grammatically incorrect. Technically speaking, you should use the word ‘whom’. But if a native speaker said “Whom are you talking to?” I would probably ask myself what I’d done wrong to cause such an extremely formal question. I would ask myself, why the person was being so extremely formal rather than friendly or “normal”.
Regarding phrasal verbs (verb and preposition), many of them can be split or not split when using a noun as the object. It’s your choice. However they must be split if you use a pronoun. The example that rich7 used - ‘pick up’ - is a good example. You can say “I’ll pick up John at seven”, or “I’ll pick John up at seven” or “I’ll pick him up at seven”. However, you cannot say “I’ll pick up him at seven” .
By the way, I didn’t find your answer flippant, just plain good advice.