So if you are a VRO player (like I am and your post seems to suggest) I would recommend waiting. 6.0 compatible VRO is probably going to require a new save based on the feedback & polls i have seen going on in the VRO Discord. The new changes to the physics/collision system is playing havok with alot of the ship mods so he is taking time to re-assess whats included in VRO by default. So not sure you could add those into an existing game later.

As for your other questions...
- I haven't seen anyone post a compatible list, but consider that the Beta seems to be getting a major patch every week I doubt most mods that do anything except "Add" functions will be fully functional.
- Technical issues are usually "Modification" functions. Things that base their functioning on changing existing things within the game. Those tend to break most redily after major patches because of updates the devs make to the code they rely on. The pure "Add" mods generally hold up better through updates... 6.0 However has an extra wrinkle with a physics system update. That apparently will require adjustment to all Ship Mods collision box systems. Thats going to break pretty much all mods that add ships until the model can be adjusted.
- You might find a better list on the Egosoft Forums. Don't think anyone has posted one on Steam.
- No experience from me... I am holding off actually getting invested in the Beta. I will wait for the full release.

There really is very little chance of getting solid answers to these questions. The problem is that each modder has to look at everything egosoft has changed to see if something needs to be changed/fixed or has been made redundant. Some mod makers wont do it because they have moved on, others because they cant or others because they dont want to. Perhaps you will find answers for specific mods because that author is active, but really we as users need to check them all ourselves.

A 'list' would have to be curated by someone that is taking the time to do this - do they do it correctly? Are their findings correct? Define 'does it work' - because a mod might not crash the game but might cause any number of other problems that arnt immediately obvious without significant testing. Anyone that posts a list of mods that are working i'de wager has just done a quick check to see if the game loads and if a mod 'works' at surface level.

As far as ship mods, I can tell you that ships shields turrets and weapons will not be purchasable because of changes to the underlying structure - this requires a fairly 'easy' change from the author. There are other much worse problems however that currently cant be fixed, modded ships will have several problems with collisions, which effects recieving damage, pathfinding and AI (AI might not be able to attack the modded ship or act strangely around it). We are waiting for egoosf to release tools for these problems along with 6.0 (it might not happen by the way, we will see). Personally I am not going to take the significant time to update my mods (several mods, multiple version across multiple sites....) for the beta while the collision issues remain, meaning ide have to do it all again after fixing those.

Thats a lot of good info on that thanks.