IMO 13 ft is too long for an island. Would you consider dividing it into two islands?

13 feet isn't an island. It's a continent.

The number of lights you use depends on how wide their throw is. You don't want distinct pools of light; you want a consistent level of light, since it's a work zone. I'd do 5, so that each part of the island is hit by at least 2 light sources (to soften shadows).

No counter material will span 13 feet. You'd better focus on finding a fabricator with artisinal skill at bookmatching stone. That many pendants is going to look like an upside down forest. It's too much. Better to use unobtrusive 4" recessed lights and let the chandelier over the di ing table be the focal point. You cannot have a zillion focal points in an open space. It's too many clowns in the circus.