Seven fruit trees will give you 21 fruits every 3 days. Since fallen fruit disappears at the end of the day, it would be best if they were planted on different days. For instance, if you planted 3 trees on one day, and 4 the next, after the trees mature you would get 9 fruits on day 1, 12 on day 2, none on day 3 (which is survivable), and 9 again on day 4, 12 on day 5, etc. I don't believe peeps will starve to death with only 2 days of hunger, so even if you planted just 4 trees on one day, it should be enough.

I think it is a random pick who moves out, but the last time I lost a peep it was the last one who moved in. That wasn't by starvation. I didn't keep an eye on the beauty of the town. Ooops. I tried to starve my peeps back in December and I don't think they died off in the reverse order of moving in. I am not at all sure, though.

I've wondered if a player could rid themselves of an annoying peep by stockpiling fruit and vegetables (peeps can't get to it in your inventory/storage), cutting down all fruit trees and harvesting all vegetables, then hand feeding everyone but the peep you dislike until the disliked one starves. It would take a while and feel kind of terrible.