Can I Merge All The Three PF Account Balances To One PF/UAN Account?

Hi
I have worked in three companies and now looking for a job.
My query is below:
Q1: Is my PF Taxable as each company created new PF/UAN account ?
Co. 1 - 02/06/2011---29/09/2015
Co.2 - 30/09/2015---12/07/2016
Co.3 - 13/07/2016--- 05/09/2016.
I want to withdraw PF from all accounts. Is it Taxable?
Q2: Can i merge all the three PF account balances to one PF/UAN account?
Q3: If i wish to withdraw PF balances from last two companies , how much Tax rate is there?

you can file transfer of previous accounts with this site with current UAN login One Employee One PF
withdrawal is not a good option, as it reduce the pension eligibility