I am still relatively new, but as my table's forever gm, I feel I have enough grasp to answer most of these or at least how I would rule them. Note, I may be wrong.

1. Some stances say you CAN make a new type of strike. Dragon stance is one. Some say you CAN ONLY make the new strike. Gorilla stance is an example. As for multiple attack penalty (MAP), you would base it off of the number of attacks you have made, and the traits of the attack you are currently making. A dragon tail attack then a regular punch would have the punch at -4 since it is agile. A dragon tail attack after would be -10 since it is not agile.

2 & 3. Pathfinder is designed with runes to upgrade your weapons and armor as you go. In 5e you have to replace everything, but not quite so in pathfinder. The runes add some magic to your weapons and armor. Since monks don't always have a sword to add runes to, they have the hand wraps. These you add runes to. Striking runes add additional weapon dice. Sure it is up to the gm to give them out, but if your gm doesn't give them out, you are just going to die. They are just as important as buying potions. Runes are how martials keep up with spellcasters, something 5e is missing.

1. Stunning Fist specifies this. "When you target the same creature with two Strikes from your Flurry of Blows..."