Ya. "Quptenkos Ēngoso ȳdrassis?" is not a question about what's happening
now, but a question about a general fact, a capability, so aorist is needed.
Ji is an article (you'll sometimes see it elided to
j'). Kraznys speaks Astapori Valyrian (
http://wiki.dothraki.org/Astapori_Valyrian_Vocabulary), which is practically a different language - just close enough that it's not totally inconceivable that the unsullied and Kraznys understand Deanerys and Daenerys understands them. Note, for example, that Kraznys starts the sentence with the question word
ydra, while in HV
ȳdrassis comes at the end of the sentence.
Meereen Valyrian, on the other hand, is very close to Astapori Valyrian, but such murky and lossy dialect that Daenerys cannot follow it (and we too are having hard time).
Hrmph. I should really try to waken Mad Latinist. I know a lot about Dothraki, only little about Valyrians.