The Luke/Wampa scene doesn't exist... It's a bit of an urban legend as Luke is in a production shot with an odd looking cannon (in his X-Wing uniform). The shot doesn't appear in scripts or adaptations.
The Wampa thing starts with Han's leaving Echo Base to search for Luke... Prior to his leaving, and this is still in ESB, Han sees Taun-Taun handlers hovering over a dead TT, and he asks what's up, but they're all perplexed by the TT's broken neck...
Flash forward to Luke's recovery in echo base and the knowledge now that there is something nasty on the planet wandering about... They are on alert for it.
Flash to R2 wandering down a hallway humming to himself in Echo Base... Wampas burst out of an ice wall and attack him. He shreaks and the noise attracts the Wampas it is found... The Rebels fight the Wampas with blasters (shots of this exist) in the halls of Echo Base, and R2 is used to bait the Wampas into a storage room where they can be locked inside... The room is given a danger sign on it.
Flash forward to the Empire arriving and the heroes escaping Vader... As they're fleeing Imperial Troopers, C-3PO in a shrude maneuver rips the danger sign off the Wampa cage. As the Snowtroopers scour the base on the heels of Han/Leia/R2/3PO, they enter the Wampa room thinking it's just any other room to sweep/clear it of Rebels... As they do, they're ripped to shreds by the Wampas.
I love deleted stuff... I wish we were given more of it actually. I'd lvoe to see the firefight on Endor in the bunker, I'd love to see anything extending Bespin and it's citizens, I'd love to see of course all the Anchorhead footage and the shootout in MOs Eisley's streets ala a high-noon gunfight.
There's cool stuff out there for sure. Oh and I'd dig seeing the Rebels on the Falcon in the Gunner Wells kicking some ass.