"One slows down, they all slow down." No.  They are brought up and synced before being put on line.  They are not affected by another unit on the grid per se, without tripping and coming off load.  There is no speed adjustment of a generator as frequency is product of rpm.  The UK runs at 50 hz.  2 pole gensets run at 3000 rpm.  Full load, half load, quarter load... 3000 rpm.  4 pole units at 1500 rpm.  Your analysis of the electrical grid misses a large fact.  In relation to the demands of the grid, the wind hardly ever blows and when it does it doesn't blow for very long or very hard.  Without a massive capacity storage system these units produce very little real power.