Translation:The emperor is stronger than the king.
"Decât", in most cases, is the exact equivalent of "than" (more powerful than the king/ mai puternic decât regele). However, "ca" is the equivalent of "as" (beautiful as a flower/ frumos ca o floare) or "like" but only when used in equal comparisons (slow like a snail/ lent ca un melc). It's an overlooked gramatical error that most Romanian people do.
I am a native Romanian speaker and I am horrified to see these kind of mistakes. The correct sentence in Romanian is "Împaratul este mai puternic DECÂT regele.", because it is a comparison. Please be careful with these. (Romanians tend to make such mistakes, because pronouncing "ca" is faster and much easier than pronouncing "decât". We don't see the mistake)
"Pot să îți folosesc toaleta?", but, imo, it sounds hella unnatural (actually, please never use this phrase; I personally have never used it & never heard anyone using it). You'd be the safest using the Romanian equivalent of "Where is the toilet/ bathroom?", which is "Unde e toaleta/ baia?".
emperor vs king.
An empire, roughly speaking, is stitching together a bunch of different places under one ruler, while a kingdom generally is one united land. The Roman empire, for instance, included a bunch of different lands which were conquered and conceptually still considered distinct although ruled together. Compare to, for instance, Sweden which is a Kingdom. But then the complexity is, the Kingdom gets some additional lands somewhere else, and then there's the Swedish Empire for a while. Then they lose those extra lands and you're back do the King having just his Kingdom.
It's a matter of perspective and can be a subtle distinction sometimes, but there is a conceptual difference there. An empire is not necessarily larger, but it will tend to be as it's a type of union essentially.