Hello,
Thank you for your feedback and for this the first post.
Technically there is no limit of connected devices to SkyElite, of course SKyElite performance will depend on the main computer (server) resources. I currently have customers running SkyElite in three tablets or Ipads and no one reported performance issues neither in SkyElite or the simulator.
The device age will count too. Very old devices or iPads may behave slow or even will not work, but the best way to know this is to test. Try it will not harm and you will know.
Simulator performance impact should be minimum or imperceptible. I saw minimum FPS impact when running SkyElite in same computer where the simulator is, but not because SkyElite itself, but the web browser taking some resources from the graphic card due the graphics. When using external devices, even better.
Hope you enjoy SkyElite.