A question from "You can negotiate anything" by Herb Cohen

Dear teachers,

The following is an excerpt from "You can negotiate anything" by Herb Cohen.

By and large, a good general rule is to avoid formal written communication where possible.

[1] I think the sentence should be changed into (a) or (b):

(a) By and large, a good and general rule is to avoid formal written communication where possible.

(b) By and large, a good, general rule is to avoid formal written communication where possible.

What do you think of this?

[2] Could you please let me know the difference in meaning between "where possible" and "if possible"?

Hope to have your soonest feedback.

Thanks and best regards,

David Kim