"She needs food" can be written: teastaíonn bia uaithi, while "she wants food" is: tá bia uaithi, or teastaíonn bia uaithi. Tá (object) ó(subject) is always (I think) "wants", teastaíonn (object) ó (subject) is "needs" in most cases, so to be sure, only use teastaíonn when you want to say "need" not want.
It sounds like a pure schwa to my Béarla ear and I can't hear any velar or labial modification near by. That leaves me a bit :shrug: over i or u. Above, people have suggested it's a mistake or unclear, which is fine as a resolution, but I'm nervous over accepting that from anything other than a native speaker. Should I be training my ear to this or passing over it?
Prepositions are highly idiomatic in any language and really don't match up at all between languages, so you're just wasting your time if you spend more than about ten seconds worrying about them!
The answer to your question, though, is "Yes, sometimes 'ó' means pretty much the same as 'from.'" Check out these examples: http://www.focloir.ie/en/dictionary/ei/from