Re: Varys’ “teleportation” - if you watch the end scene again you will see that there are Martell ships as part of the fleet by that point. So it was nothing magical, he just got on a ship in Dorne and sailed to meet the fleet.
It just seems strange because there must be weeks of time passing between scenes that were shown just a few minutes apart. The whole last episode probably occurred over several months, since Dany is in Mereen at the beginning of the episode, but at the end, her and her fleet are probably in the Narrow Sea already.
The passage of time is the explanation. Sometimes things happen in the blink of an eye, when in reality it just took time.