Affirmative agreement of verbs

[divineacclivity]

Wrong: I have seen the film and she also has.
Right: I have seen the film and she has too.
Right: I have seen the film and so has she.

Barron (a GMat preperation book) states the above.

I've always used the first sentence more frequently than the 2nd. Is it wrong? If yes, why?
Thanks in advance!

[divineacclivity]

"I also do sketching."
Which of the following does it mean:
1. Someone does sketching and so do I
2. I do sketching and something else too

"I do sketching also" --> does it very clearly convey the second amongst the above two sentences

Could you please suggest a link or something that can give me a fair idea on the difference between the usage of the two: also, too

I also want to know if GMAT could base right or wrong on this confusing topic?

Thank you in advance!