Wow, that took a while to read through!!
A few things to add...
1. As "Méchant Malade" noted, using lighter line helps force us to bring fish in slowly, it also increases diving depth on our lures. So rather than using 20 pound test and a downrigger to get 40 feet deep, try using 8 to 12 pound fireline and run a stretch 20 on a long lead. Keep the boat moving forward slowly and bring that fish in, snap a pic or two and watch it power back down on release. So, are riggers really necessary? By the way Méchant Malade, your english is fine, I think we all understood your message.
2. As for handling fish, "Walleye" mentioned not squeezing the fish.... I want to mention not putting fingers into the gills. We all see pictures of guys with hands and fish that are very bloody. I have never seen a walleye bleed like that from hook wounds. I have seen them bleed like that from clumsy fingers mashing the gills into the rakers. Fish bleeding from the gills are likely mortally injured. So even if you bring it in slowly and avoid the over-inflation, you can still kill it with one finger. Careful handling, a wet cotton glove on the tail and a hand under the belly are much less damaging than hoisting a 10 pound fish by it's gill plate, what happens when it starts to thrash?
3. Fizzing is a method used to release the pressure from the bladder. I will never try it unless I am shown by someone that knows exactly what they are doing. I watched a biologist fizz a fish at perfect vue this spring when someone brought in a stressed fish for the derby. the fish was on it's side, but still alive. He spent about 15 to 20 minutes playing with this fish and SLOWLY letting gas out of the bladder through a hypdermic needle.