36 month visa Confusion

Question

Hi, I need some help. I'm a little confused about this instructions i read:

""""If you have a tourist invitation that is only valid for 30 days, you should still specify the intended dates of your travel during the next 3 years. Don't worry if your plans change: eventually you will have a 36-month visa, which enables you to stay 180 days a year in Russia and you will be able to travel there when you want""""
 
Should i enter the 30 day invitation's day range and specify elsewhere on the application that I want a 3 year visa?

Also, i hear that if you apply for a 36 month visa they will require 36 months of health insurance. How can anyone afford this insurance  ($1800) even though you can't stay more then 180 days per year?  

Please, any help will be appriciated.