the rules are

1. The rollover

You can only rollover once from traditional IRA/401K/ROTH IRA to HSA.  You'll have to be eligible for HSA at least 12 months before the rollover, this means you'll have to be on a HDHP plan for one year. 

2.  Advantage of HSA

a) no required minimal withdrawal; b) medical expense is paid without paying income-tax. 

3. Withdrawing for non-medical reason from HSA

a) you'll have to pay income tax for non-medical withdrawal  

b) if you are under 65, you'll have to pay 20% penalty for non-medical withdrawl

c) if you are over 65, you don't pay 20% pelanty.