Stymied is translated as, eng>port, "frustado" very similar to "annoyed" and the same as "frustated"
So, in the first sentence it means "And many people immersed in technology are just as stymied (the people that immersed in technology, as nowdays it is present everywhere we go, they got and are constantly annoyed about that, maybe because how it sometimes turn our lives into a big mass only because we can't find any WI-FI signal and your 3G isn't working either and you nedd to send a message to your boss so that you can have that one promotion to boost you life).
In the second one "Have you ever been stymied by your school work in some way?"(someone is asking if you have ever been annoyed by all the work school sometimes gives to students and seems like they don't even care about you, sometimes this is very frustating).
Hope that I made your doubts go away.