Thanks for posting this and being open to learning from your mistakes. I totally held my breath as your buddy was pulled under that strainer. Your group was certainly lucky that everyone made it home safe. I'll offer some insights just FYI.
As far as the stream crossings, there are a few techniques that are useful, but nothing that would have let you cross in waist deep water. First, avoid the barefoot crossing if you can't see the bottom. I like neoprene socks, but in a pinch you can always pull your boot insole and put it in a regular sock. I deep gash in someone's foot is a trip ender. TO cross more safely you can link arms or oven better form a triangle/square and all cross together. Kinda ruins the hero stream crossing pictures, but it is much safer. Also, with solo crossing I like to face upstream and sidestep as it provides greater stability, control, and keeps your legs from being crossed by the force of the water. Make sure your packs are always unbuckled so they don't drown you if you do go down. Also, logs and anything unusual in the water should be avoided at all costs (even though they seem so tempting).
The other thing I would encourage you to think about is your group's dynamics and the role you played. I would imagine that someone in your party knew what a strainer was, knew about water crossing depth, for that matter, could figure out that standing in front of a swinging axe was a bad idea. So the question becomes why did it all happen and how could all of this been prevented or at least, the danger minimized. Your group's desire to be home for father's day motivated some poor decisions, but at the same time those decisions were still acted upon and the questions of how/why you let it happen are important.
While these are big questions that can't be answered quickly, one little trick I use is to have a 2 minute-ish time to play devils advocate when making risky decisions. You designate half the group to argue for something and half to argue against. If you agree to to this at the trailhead it keeps you from having to be the jerk if you want to argue about a risky decision.
Best of luck and go make a donation to a restoration project for chopping down those trees.