Is electrical already in the ceiling for lights? It appears to be new construction in photos. I would go off of that first... only due to what spacing might be set up as already. Personally I would go with 2 larger or 3 smaller ones. It doesn't look like there is any seating from the photo so they wouldn't be in way from that perspective. Just line of sight from the rest of the kitchen outwards.

If your drawing is to scale, then proportions look great.

Yes, I had to do that too. Tape the island size on the sub floors or build one from cardboard...this will bug you if you get it wrong. Or just go with what you were reading as a recommendation. Good luck! Make sure that you have plenty of aisle width planned, the island electrical won't let you push the cabinets a few inches either way.

Some photos are attached. Island top is 108" x 54", waterfall top, honed black pearl granite. White cabinets. Ceilings flat 9'. Kitchen is open on 2 sides. Need advice on size of pendants if using two oversize pendants. I'm thinking width somewhere in 24" - 36" range depending on height, shape etc... I don't want them to look too big nor too small. I can use 3 pendants also, not set on 2 or 3, not sure. There are photos below of the type of pendants I'm leaning toward as of today but I'm open. The backsplash and hood behind it will be a pretty bold porcelain and I don't want to distract from that either (photos below).