re: People in plural and singular forms, "people" in most usage is plural, but it can be singular when it is used to refer to the entire group in an inclusive manner and can in fact take -s plural form, like the "All the peoples of the Native American tribes." That usage groups all the people of an individual, distinct tribe as a singular "people" and pluralizes the word by adding -s to refer to a collection of the tribes, composed of those individual, distinct tribes.
And colloquially speaking, "there're" is a very common contraction in American English. (can't say about England English).