Walter Smith hopes to bring some stability to Rangers after his appointment as non-executive chairman.
Smith replaced Malcolm Murray in the latest Ibrox boardroom shuffle, with the latter remaining as a non-executive director.
And the move completes a dramatic year for Smith, who was part of a consortium which failed to buy the club's assets after they entered the liquidation process last June.
The 65-year-old was then appointed as a non-executive director by Charles Green, who stepped down from his role as chief executive in April after allegations of involvement with former Rangers owner Craig Whyte.
Green was cleared by an independent inquiry carried out on behalf of the Ibrox club, and remains majority shareholder in Rangers.
Smith said: "Unity among the directors is vital. We must all be on the same page as often as possible.
"We won't always agree but Rangers, this club and our fans must always come first.
"It's a great honour to be asked to take up this position.
"However, no one should believe that I see my role as a passive one. That hasn't been my way in the past and it won't be my way in the future."
Striker Dodds and goalkeeper Johnson put pen to paper on two-year deals while midfielder Birchall and first-year professional Morris have signed one-year contracts.
Manager Micky Adams told the club website: "Preparations are continuing in earnest for the new campaign and I'm really pleased that all four players have decided to commit their immediate futures to Port Vale Football Club.
"Louis has been an integral part of the squad, both on and off the pitch, for a number of seasons and I'm certain that he will continue to make a positive contribution to the team in League One.
"I've been impressed with Chris' attitude since he returned to the club in January and anyone who has seen him play will know how hard he has worked and the impact he has made on the team.
"Sam had another good season for us and impressed in the fixtures he played in. He is a young player with a lot of potential.
"For Tom, this is the first step in his professional career and I know he will be going all out to make a positive impression. He has earned his professional contract and I wish him well as he steps onto the first rung of the ladder."
