In a nutshell.....there is no easy answer along the lines of what GWT75 said.
All depends on time of year....what may be "running" etc. There is no quick answer to your questions aside from much like GWT said, you're going to be down DEEP during the winter.
If I were you I would cover some water and troll with a diver as noted above during the summer/early fall if targeting salmon when they are moving through your area. A diver is NOT going to get you down deep enough for the resident fish which we target during the winter but you may find some migrating fish at other times of the year which will be higher up in the water column. If it was me in your rig I would be trolling a diver with a flasher with a hoochie, spoon or bait behind it. I don't recall which company makes them but you can get divers that are very bright/iridescent like a flasher allowing you if you so choose to remove the flasher from your rig and just run the lure behind the diver.
If you were going to try and power mooch.....do a search online or on YouTube as to how it is done. LOTS of tutorials on everything you can imagine with respect to salmon fishing on the big ole Internet.
Personally I only recall catching Pacific Cod during the spring fishery and that has been either near Gabriola area or out at the Hump which is south of Bowen Island in the Strait. Not sure if you are aware, but if you are catching dogfish be very careful of the spine on their back behind the dorsal; you do NOT want to get jabbed with it.
Hali.........if you really want to eat some pick some up at a store. Halibut are for the most part only caught as a VERY, VERY, VERY rare by-catch on this side of the Strait.
Will salmon take a shiner? You never know......people catch salmon on all sorts of rigs/lures/bait.