I am getting clicks but no impressions, I know that means there is something incorrect in my links (pixel graphic), but will that affect it tracking sales and leads?
Some text links, but not all have an impression tracking pixel in it. If you take a look at a few text links some will be noticeable longer and have two url's in it meaning it has the tracking piece too. It's not by advertiser whether they have the impression tracker in there, it's by link itself. If you're looking for the impression piece, just take a look at all the different text link code they have and see if one has the impression pixel component.
Yes, I'm aware of which links that have the impression tracking pixel in it, which is all of them (with the particular advertiser). Will it affect the actual tracking of the leads and sales, if you omit this piece from the url?