Yes, 10 hours between flights would be enough time to visit the Acropolis (probably the primary attraction for most tourists) as well as one or two of the other sites/sights around Athens such as one of the Agoras or Mount Lycabettus - though you could spend a lot more time at all of these.

If you have just travelled around Egypt on your own, I don't think you have to worry about Greece.

However, unless you are in your early 20s and eager to see as much as you can as quickly as you can, I don't know how much you will be able to take in after a 0310-0610 flight and having to get to the airport before that. Bearing in mind that you will need to deal with entering Israel and figuring out how to get to your accommodation the same evening! And as you are concerned about safety, being tired also lends yourself to being distracted more easily.

5 hours between flights doesn't really give you enough time to do anything as the airport is around 1 hour from the city and it's relatively expensive (€12 return by bus or €20 by metro) to get there.