Since food is a low priority in a short term situation, my survival fishing gear is more of an afterthought than a comprehensive fishing kit. Carrying a few basics takes very little weight and space, so it doesn't hurt to have some hooks, line, etc. but I don't go much farther than that in my pocket kit.
One thing that is very helpful, at least for me, is a fishing knot diagram. I do not fish enough to be handy with these knots, and it is surprisingly hard to keep a hook on a line with basic scouting knots.
I also think a tied fly lure or two is nice to have in case natural bait is scarce, and these are small and very light.
If I really wanted to be organized, I would have a swivel pre-tied on the line and the fishing hooks snelled with about 6 inches of line on each that would just clip into the swivel. This would eliminate most of the tedious and delicate knot tieing in the field, which might be difficult with cold or injured hands, etc.
Being able to secure a loop to the tip of an improvised fishing pole and pass the line through and down to your hand makes a more sophisticated rig capable of handling larger fish with less strain on the line. Some carry a commercial rod tip for this purpose, but a safety pin can work as well.
Your idea of a trout line is a good one that I have seen in some survival manuals. Speed hooks and nets would also probably increase production, but now you are talking about more weight and space in the kit. You have to weigh that trade-off for yourself. Those kinds of things wouldn't make the cut-off in my pocket kit, but if I were preparing a larger kit, they would be nice to have. It would depend on the specific purpose of the kit and I would definitely prioritize fishing below additional shelter, water and signalling items.