Hulme, 20, was Widnes' young player of the year last season, scoring eight tries in 11 appearances, while Lunt also has first team Championship experience, making five appearances for the Vikings last term.
Hudson is no stranger to Crusaders coach Clive Griffiths, having played under him for the Great Britain Students side that beat Australia last year, playing alongside existing Crusaders' Owain and Iwan Brown.
Griffiths said: "We're delighted to bring these three exciting new exceptionally talented players in squad. All three players are versatile which is a big boost to us. All have played to really high standard of Rugby League and they'll be a great addition to our squad. They're all born and bred League and have been looking good in training. We're lucky to recruit players to this quality."
Griffiths also said that the club's second open trial this Sunday at Queensway in Wrexham was another success.
"We were right to hold it as, due to number, we weren't able to see everyone last time," he said. "We'll certainly be offering contracts to a few of them."
Sheffield are out for revenge when they face Bradford today in the CHampionship Shield Final.
Despite not making the grand final next week Hull FC head coach Lee Radford was pleased by the manner in which his team came back against Wigan after looking dead and buried at half-time.