Must I use my Russian Visa within a certain number of days?

Question

Hello. I'm an American citizen hoping to apply for and get my 3-year Russian multiple trip visa in Seoul, South Korea.  Two questions:

1) Do I need to provide any flight information; and 2) once I get the visa do I have to use it within, say, 90 days?

For a Brazilian visa, for example, you need to provide a flight reservation and once issued, you have 90 days to activate it; i.e., if you don't use it within 90 days, it becomes invalid and you have to re-apply. At least that was the case when I got my last Brazilian visa.

Thank you in advance for any help.