I haven't read all the posts but these are just a few thoughts of a guy who has been riding a very ling time.

You need to have the tools and skills to change tires on the road. It's not difficult but the road is not the place to learn. Flats happen. No being prepared is thumbing your nose at the gods. Might work for a while. There are U-tube videos I'm sure. You can ask at bike shops or (better) bike coops about lessons. Go to Sheldon Brown's website.

Kendas are mediocre tires. Might not be the cause of your issues but why not run good ones. Panasonic Paselas are quality tires. Not light, super fast but solid all-around tires that pick up little glass and very rarely have defects. I'm not saying you need to ride them, but use them as a quality standard to be at or above.

The line to ride - a balancing act between debris, road hazards, traffic, being seen ... Debris - obvious. The further left you ride, the less, almost always. Road hazards - ditto but more exceptions. Wet painted lines. (Fog lines) Cracks running parallel to the road. Traffic - not a simple answer. Those that are not texting will see riders ahead but may well not notice riders to the far right. If you want to be seen, move left! On quiet country roads, I stay well away from the road edge to be seen. Pull back when I hear or see in my mirror a car approaching from behind. Haven't been hit yet except on purpose. (We have folk here who shouldn't be driving. More than one of my intentionally close pickup truck passes were by drivers well known to the local police.)

The best line to take can change. We have roads where I live with big variations in what the right edge looks like. On some I vary my position as much as two feet and if I need more, I'll take it. But when I do, I two things if at all possible. I make the line change slowly, starting way before I get to the point where I need it so I am doing nothing sudden to surprise cars. And I often signal my move with the left arm turn signal.

And probably my biggest advice - don't consider the right edge of the road your friend. It is the source of most flats and many crashes. Also opening car doors, balls, kids, animals ...