Retreat paths are a foundational part of COH and its critical that they work as intended. Its possible Item 2 doesnt go anywhere because of its complexities, but Item 1 is a no brainer for COH3.
I'm grateful to see the effort you are putting into opening up this topic. I know a lot of people have complaints about the retreat pathing both players and map creators.
I'll just break down my opinions based on your points in simple form:
My personal opinion is that retreat is already in a good place conceptually and in design. Mainly because it allows you to bring units back to base quickly for reinforcement or healing, which importantly helps with the time pacing of the match. I feel that is the sole purpose of retreat and supports the games squad member and unit health feature in COH2.
I have never been fond of the idea that retreating as a feature should allow you to save units that you have played badly or taken risks with. Flanking in enemy territory etc has risks which are already helped out by faster running time on retreat and damage reduction and I feel that's a fair compromise already. So I don't feel that allowing players to predict retreat will add anything to gameplay. It could possibly lead to more frustration that someone could just run in with masses of infantry and know they can easily retreat to safety. The outskirts of the map have always been higher risk areas because of this and provide necessary opportunities for players to punish opponents.
Despite my thoughts on point 1, I do think that adding waypoints for retreat on some maps (I am thinking more of bigger maps such as 3v3 & 4v4 maps) may be a positive addition. I think this because the maps can be made large enough that flanks etc can still be made.
Let's be completely clear, some factions (UKF, USF, OKW) already have units or buildings which can toggle abilities to alter retreat pathing. If you were a god tier player, you could already use something like the major to alter retreat paths in the game, so the idea of way point markers is no different as long as they don't prevent you from punishing your opponents for risky flanks that don't work i.e waypoints that hug the edges of the map.
I would hope that there would still be a use for abilities which provide retreat path changes such as the Major does as I think the more opportunities you put in the game for a player to change things up, the more potential an RTS has to be diverse and interesting.
As a suggestion for retreat paths I had previously thought of a mechanic where retreat is a 'mode' where you press the button and the squad is immediately put into retreat mode with the same current speed and damage reduction values. It can't fight, but breaks suppression factors etc. Then, you must manually run that squad back to base where retreat mode only deactivates in base territory. That would then allow players to retreat in any direction as they see fit and completely remove any pathing issues.
Please note though, whilst I suggest this, I really don't think it's necessary.