are they correct?
1. Thanks to him.
2. Thank him!--I want to say thanks to the third person
3. B told me that A asked B to convey his regards to me. Then I said Thanks for these or thanks for those.
4. Thanks alot! Tom!

Thank you!

Question

are they correct?
1. Thanks to him.
2. Thank him!--I want to say thanks to the third person
3. B told me that A asked B to convey his regards to me. Then I said Thanks for these or thanks for those. 
4. Thanks alot! Tom!

Thank you!

Answer

Robin:    1 & 2 seem to read fine.  But....

3. B told me that A asked B to convey his regards to me. Then I said Thanks for these or 
thanks for those.

[Corrected]:

3. B told me that A asked B to convey his regards to me.
Then I said;    "Thanks for  those.  [Those "regards".  You could also say; "Thanks for that." [Thanks for  the "conveyance".]

.

4. Thanks alot! Tom!

Corrected:    "Thanks a lot, Tom!"