It all depends on where you want to go and what you want to do.
Since you already have a 4wd truck, just go somewhere and see how it does. A basically stock truck can take on virtually the entire American desert, the easier trails in Moab and other "4 Wheel Drive" destinations. Spend a year learning what you like, and fixing all the little stuff that doesn't currently work on your truck. Get some good tires, and just go. Don't focus on how much stuff you "need", just go.
Once you limit out on what your truck can do, then is the time to make the decisions about your future direction. If you are considering dual cases (an absolutely game changing mod by the way) then you are also near the point of a soild axle swap, and that, I would not do.
Just me personally, but if you are at the point of considering a solid axle swap, and can't do it yourself, you will be time and money ahead to just switch platforms. Buy a truck with it already done and sorted out, or buy a Land Cruiser that will have stock heavy duty axles/steering from the factory. [It is really tough to beat an FJ60. They are cheap to buy, tough as nails and when you want dual cases, Marlin makes one for it!]
The one thing on your list I would do now, is a rear locker. That can be extremely helpful even in places you may go in a basically stock truck. For your rear locker there is really only one choice-ARBs. They are transparent mod and drive normally the 99% o the time you spend commuting or highway driving. The front can wait, as a locker will add more stress to your front axle components, and they are not super strong, so....
One thing not on your list, but should be an early purchase, is a winch. Then if your enthusiasm carries you into some place you shouldn't be, you can get out with out a huge strain on your drivetrain. Hard to beat an M8000 for a good intersection of price and meeting the need.
In summary, start travelling as soon as your truck is working well and all maintenance is done and up to date. Learn what you like. What you have will go a lot of great places on 31 inch tires, with minimal chance of breakage.
You will likely find in the end, that you need to mod your truck as much as the friends you go with, so choose them carefully.