I only suggest this deck if you have already a fully (or two)upped Fg grinder.
The rewind is for better use of time quantum and to get rid of nasty creatures like oty, also against other rushes it helps because you can slow him by rewinding his stronger creature.
The damage input is not a problem,you can win this decks full of sog's, miracles pretty fast.
The quicksand slows your opponents a lot.If you have played Seism , you have Against control decks or non-speed rainbows, it usually means that you can rush them before he can set up his defences. Also gives you an oportunity against hope-Rol decks, because you have to rush them before he can play a fractal and a hope.
Against speed rainbows and pillarles is clearly a useness card, but because of the IA, you are going to win most of that matches anyway and helps a lot against other kind of decks.
I don't know the upgrade order, because I usually have more than 80.000 electrum ready and when I like a deck I buy all together and then I try it.( well I have six copies upgraded of most of cards in games, only I don't have six copies of cards that are not very used like purify,or cards that are not in Fg's spins and are not useful)