Do any particular races have more of a genetic predisposition for developing alzheimer's?

Not really. Regardless of race, roughly 45% of pts by age 85 yrs will develop alzheimer's. A few families carry genetics which result in early presentation, but most cases, by far, are sporadic. This is an "equal opportunity" disease which occurs most often as a risk of the elderly, and any person of any race who ages is at risk.
Not Really. There is no direct racial link. However, people with diabetes & cardiovascular problems tend to be predisposed. We know that there are higher rates of diabetes & cardiovascular problems in some ethnic groups but probably more due to circumstances than an actual genetic cause. So there is an indirect correlation to alzheimer's that isn't genetic.