Is a Lemur related to the raccoon?

Only in that both are mammals. Lemurs are primates, like monkeys and apes (including humans), whilst raccoons are carnivores (order Carnivora). They are NOT mustelids, as BWANA says - Mustelidae is the weasel family, which includes badgers, otters, wolverines, mink, martens and so on. Raccoons belong to the family Procyonidae, which includes kinkajous, ringtails, olingos and coatis.

They're related but only very distantly. Both of them, of course, are mammals, but the ring tail of some lemurs is only a coincidence with the ring tail of the raccoon. The raccoons are in Order Carnivora, along with while the lemurs are in Order of Primates, which also includes people and monkeys ... except for the 2 species of "flying lemurs," which are in Order Dermoptera, all by themselves.

NO, they are not related. Lemurs are Primates, while Raccoons are Mustelids. Lemurs live in Madagascar and Raccoons live in the USA. They don't even look reasonably similar, and the skulls are entirely different. Raccoons are omnivorous in their eating habits, while Lemurs are strictly vegetarians.

The "only" thing they share in common is that they are both Mammals and that's it.

nope

yes.