Question about Samsung ViewFinity S9 - S95UC S49C950UAU

Yes, but the images must come from different sources. You can't use it as two monitors on one PC (e.g. with a home office laptop that can't manage the resolution).
Source: tried it myself and confirmed by Samsung!

Yes, this monitor has both functions according to the Samsung website:

Picture-in-Picture
Yes

Picture-By-Picture
Yes

Lg