Didn't / Hadn't / Haven't

[jack]

Are these correct? If not, why? What do they mean?
1. I would be playing basketball by now if I hadn’t slacked off.
2. I would be playing basketball by now if I haven't slacked off.
3. I would be playing basketball by now if I didn’t slack off.

4. I would read more if I didn't have a TV.
5. I would read more if I hadn't had a TV. (Is this wrong? is it because if you're talking about the past, it should be 'I would have read more if I hadn't had a TV.'? )
6. I would read more if I haven't had a TV.

[Tdol]

1 & 3 are correct. 1- past action, present result.
3 imaginary present

[jack]

Thanks.

[jack]

2. I would be playing basketball by now if I haven't slacked off.

I know this one is incorrect, but could you explain to me about what it means? So I can understand why it is incorrect. Thanks.

[jack]

Are these correct? What do they mean?
1. I could have done that myself if I knew what to do.
2. I could have done that myself if I had known what to do.