1) No. Harmony's last multi-room remote (up to 6 locations) was the 890 PRO which was discontinued about 10 years ago. All models since are 1 active room/activity at a time. Best you can do is jump out to device mode then back to the current activity without running it again, or combine all devices for both rooms into one activity, or get 2 remotes - 1 for each room. In my Harmony systems, I count on having 1 remote per room and try to program them so they don't interfere with each other.
2) Yes. But I assume you mean Netflix, not Netscape. I haven't seen Netscape for over 20 years.
3) Generally, yes it usually has a full set of discretes, but not always. Most of their Sony devices probably have all discretes. You sometimes have to tweak the device settings in the Harmony software to force them to use discretes instead of toggles, but that usually happens automatically.
4) That will work fine.
5) If you have pronto hex for all your current devices, you can email any missing codes you come across to Logitech and they will add them to your account.
If you want the same sort of flexibility you had with Pronto, URC would be a better choice.