Which R&D-related expenses need to be capitalized?

I am confused about which R&D expenses need to be expensed vs capitalized. I know that for example wages, supplies and equipements should be capitalized, but how about the following?

 

1) Payroll Taxes related to R&D employees

2) Lab Rent (I would imagine not but I am not sure, since rent is already "amortized" in a sense, it's not like you are buying a piece of equipment)

3) Health benefits related to $&D employees

 

Thanks for any insights you can provide!