Vinyl flooring - expansion and impact sound insulation

Hello everyone,
we have now decided on a vinyl (or "design") floor from "FloreverSpa." Does anyone have experience with this?
I spoke with two men at Obi and brought up two topics that I would also like to discuss with you.

[*]One person said I could use 1.5mm Selitbloc as an underlay beneath the 5mm vinyl layer, while the other said that only Acoustics Floor Protect100 (1.8mm) is suitable under this floor. The prices are similar, but I am still confused by these contradictory statements.
[*]And then we have the "problem" that we want to equip the living room, hallway, and storage room with it. Basically, I have a good 5mm space under the baseboard for everything to still expand. A transition profile will go under the door to the storage room. However, between the living room (33.5 m²) and the hallway, I would prefer not to have a threshold because there is a large passage there. Allegedly, this cannot be avoided. Do you have any other suggestions?

Thanks and best regards

If there is a joint in the screed between the living room and hallway, you must also transfer it to the covering. Or at your own risk, own liability, etc., basically taking a risk.