Is this similar to a "korean spa" where guests lounge and take advantage of saunas at their own pace once admission is paid?

Yes. But not as much space to relax as a Korean Spa

Is it working on which street is it? Ticket value? Is it totally naked?

Yes, though with very few luxuries/amenities. You sweat and dip and shower and maybe get a scrub, grab a couple Russian beers and some eats.

Lol. Spartan indeed. Yes, once you're in you can wander around the various rooms at will. Make sure you try the cold pool!

Yes Better its more real. Korean spa more fancy.

Correct. The place is a little "spartan" in terms of interior.. so the "lounging" aspect of it might be a little disappointing (though the sauna is great... very few places have a proper 100c+ dry saunas)

There is a dining area in the front. There is a roof area for smokers and to cool off and nap in the cooler months or warm up after a dip in the hypothermia pool in the warmer months.

Spartan is accurate Stewart, however, if you can get pass the spartan look, then you will love this place.