One thing to keep in mind is that staffing of transit desks is spotty. In theory you don't have to clear immigration and you can just transit into the departure hall air-side. In practice, there can be zero people at the transit desks and you will be shunted to immigration and have to go land-side and clear security again to get air-side. I had no problem doing this last time despite not having a visa but it was quite time-consuming. Also, my 2nd flight left 30 minutes early and I only just made it despite having 2+ hrs layover.

I've been to lounges but I was traveling business. My recollection is that they are all business/first lounges unless you have some membership from your airline.