I'd template the existing and compare it to the new as the first order of business. That's how you'll know how much work is involved.

No, it won’t go with your cabinets. Your neighbors counters usually are pared with white cabinetry.

This would be a total mismatch in my opinion..

I like what you have now better with your cabinets. But, if you love it, measure everything to make sure it will fit - and you'll learn how much extra work/expense will be involved. Ex: will you need a new sink? how much of the backsplash will need to be replaced? etc....

Free is not always FREE!!!! Take a cabinet door off and put it next to the new granite and post a picture. Right now I would say it will not work

I really don’t think the neighbor’s countertop will work with your cabinets.

Just because you think the kitchens are identical does not make it so. You still need to measure and I have to agree the one you have works much better with your cabinets unless of course you are having your cabinets painted. But an actual measure of all the pieces will be needed for sure if painting is in your plan