Question .. Player one bets $400 , player two calls , player goes all in for $450 , can player one raise ?

Yes, as player 2 is still in the hand. If player two folds then it will be a showdown and head to head. If player 2 calls then a pot will be created of $1350 (3x$450) and player three can only win at most this pot. Player one and two will then play for a sidepot of whatever the extra chips end up being. (if player one reraises by $100 and player 2 calls then a side pot of $200 plus further rounds of betting will be contested only by players one and two.

If at any point on the flop, turn or river player one or two folds or goes all in, cards will be turned up for everybody and the rest of the cards will be dealt.

Yes he can raise and more detail has been described very well by Rankles.