what you said

[navi tasan]

1) It helped me a lot what you said.
2) It helped me a lot, what you said.

3) That helped me a lot what you said.
4) That helped me a lot, what you said.

Which of the above sentences are correct and correctly punctuated?

 

[emsr2d2]

Only 2 and 4 are correctly punctuated. However, note that a native speaker is very unlikely to say either.
What you said helped me a lot.

 

[navi tasan]

Thank you very much Emsr2d2,

A follow-up question:

Are sentences 5-8 correct?

5) Do you know what it indicates, what Don did?
6) Do you know what that indicates, what Don did?
(Do you know what Don's act indicates?)

7) Do you know what it indicates, the way she's looking at you?
8) Do you know what that indicates, the way she's looking at you?
(Do you know what the way she's looking at you indicates?)

 

[emsr2d2]

They're all possible, with the same caveat I gave in post #2 regarding whether a native speaker would use any of them.

 

[jutfrank]

It's common and natural to use sentences like this that are fronted with a pronoun that is later specified with a phrase tagged onto the end, whether that's a 'wh'-clause or a normal noun phrase. Since it is just a tag, though, a pause/comma is necessary, to show that it's not syntactically connected to the other part of the sentence.