Lots of good advices, thanks to all.
Regarding the wind strenght/boat issue, i'm quite familiar with it, i've sailed around cyclades for several years in summer, but i wasn't kiteboarding yet.
I like a lot the boat option as it allows a lot of flexibility, gives you more choice of spots, less crowd, etc.
When i was learning i went to Paros, at Pounda, and from what i remember judging now with experience it was quite a good spot, not too much crowded, while Mikri Vigla looks to me like a super packed spot, and i tend to avoid those spots as it's almost a 100% chance of messing lines with someone....
I'm still not clear on how to rig on a rather small boat in case, but i guess more than someone have already figured that out
Any more info/updates, i'm here, thanks a lot to all.