As far as I know from 2006 Russians require a visa. For your relatives you can apply for a visa, submitting all required documents- prove of relationship, letter from the employeer. Visa handling time is only 2 days. Results can be seen and printed on Hukoomi- online government system.
Tourist visa is issued for 1 month and can be extended later. However for visitors staying more than 1 month medical check up is required.