Product selection help when doing taxes for myself and one family member

Hello,

I have read several times which product to buy but am still a bit confused so would appreciate advice on which product to purchase and use.  My situation is rather simple I think.

My end goal is to e-file the Federal and State tax returns (same State both MA) for myself and my Sister.  I already settled that I need the Premier product level.

My questions are

1. Should i buy the CD version or the Online version.?

2. Under either the CD or Online solution will Turbo-tax pre-populate my Sisters State return with her Federal info once I get to that point?

3. Last year we both had separate Online Turbotax accounts - will this confuse or complicate things as i see even for the CD version you need to create an online account (should I create new ones if the CD product is the right solution?) 

Thanks to anyone willing to take the time to guide me.

Peter