This sounds like a good and apt use of person and tense changes–they aren't arbitrary, and they indicate either a change in POV or a change of setting/state of mind. The typical rule against tense and person changes is because they introduce discontinuities into the narrative voice. But in this case, that's a good thing.
Of course, it still needs to be done well. Both changing POV and introducing a dream sequence need to be done with caution. I personally dislike a changing POV, and it needs to be really necessary for me to accept it. Similarly, while I happen to like dream sequences, many people are (justly) suspicious of them, so make sure you really need it.
The potential problems are from the techniques themselves, however, not from the way you are indicating them. Changing POV breaks into the suspension of disbelief that comes when you start to identify with the book's POV. It's not something that happens in real life, so it's an extra mental adjustment for the reader. Similarly, dream sequences are perceived by many readers as corny and overused. None of this, however, is to say "don't do it." Both techniques can be very effective if used well (and probably sparingly).