401k Backdoor Roth conversion and pro rata rule

Hi There, 

1. I would like to rollover my old employer pre-tax 401k to a rollover IRA.
   1. Is there something called rollover IRA Vs a traditional IRA or are all these the same things? 
2. I contribute pre-tax max to my current 401k.
3. I contribute additional after-tax contributions to my current 401k and immediately convert them to Roth 401k. 
4. If I do step 1. above and leave the funds in the rollover traditional IRA (pre-tax money from previous employer's 401k funds are in this IRA account), will pro-rata rule affect my contributions in step 3 Roth conversion?

Thanks!