Sporades are wonderfull islands at spring. I Will be back to these islands next may and then to north Aegean. To answer the question : mooring
is easy and you have a lot of possibilities, but no "real" marina. In Skiatos, you have different renting
bases along the quays of the natural port, so you will find what tou could need. In Skopelos you have a port with a long quay where you can get water
and electricity (a small truck can deliver gas oil). In other places it is "mediterranean style moorings or anchoring" as you say.
I suggest you to buy the Aegean Pilot Guide (Imray) to get all detailed informations you need.
In summer it will be of course more crowded... But less windy than in central Aegean...
If you have other questions do not hesitate !