Wilson Darts, Zzingers, Spinnows, and Luhr Jensen's jumbo Crippled Herring all work well. Size depends on depth, current and wind. Try to use the lightest jig that stays close to vertical and on the bottom. This allows you to slowly and steadily yo-yo the jig up and down. An occasional pause followed by reeling twenty feet, then free-spooling to the bottom will draw strikes when nothing else will.
Color depends on the angler and fish.
Choose one, fish with it and see if the fish respond. If not, change colors. A longer rod only increases the fish's leverage which undoubtedly will gouge your mid-section unnecessarily and cause you to bend your back. A fighting belt and lower back support belt will ensure you have a more comfortable fight. Remember, halibut fishing can be hard work, but it should never be back-breaking.