I’m not sure what you mean by playing without markers. There are markers on the board – or do you mean using that marker chart to track IPCs?
[EDIT: I just realised you mean the chips under the units that count as one or five of that unit, depending on colour. I prefer to play without them if possible, it adds to the aesthetic value and it makes it easier (IMO) to remove individual units that die during battles]
In regard to paratroopers, I am sure pretty much everyone here wouldn’t like using our rule since it makes the game unrealistic, but we use it because we have found it to be more fun. It opens up so many more strategies, and you always have to be alert as to what the enemy can threaten you with. That’s why there are so many men on the board – leaving a territory empty is asking for an enemy paratrooper to take it without a fight.
You are right that you could add specific rules for paratroopers to make it more realistic (like the rules you’ve suggested in your post) but we like the simplicity of our rule whereby a paratrooper can be dropped anywhere that the bomber can make it without needing to worry about the question of supply.
In any case, it is extremely rare that a paratrooper will be dropped into a territory that is cut off from the front line. Generally they are used to bolster numbers in an attack on the enemy’s front line, or to attack the territory just behind the front line while the main army attacks the front line itself, creating a salient into the enemy’s territory.