Jim -
I will pass on to you some of my knowledge of polymers vs. carnauba waxes. It kind of sounds as though you are looking for what is best for your car and your current situation.
First off, there is a significant difference between polymer/sealants and carnaubas. Polymers are synthetic/man-made and carnauba wax is found naturally (although you could never use it in it's natural form without processing it first). A polymer/sealant is in essence a plastic. It "works" by bonding to the paint finish with a series of molecular bonds. A quality polymer/sealant contains no wax or oils. Examples of quality polymer/sealants are Klasse Sealant Glaze and Zaino. These products contain no abrasives (or "fine grit" as you stated) at all, with multiple coats they serve to fill in imperfections, although proper paint prep is crucial to excellent results as with all detailing type products. A quality sealant should last between 4 to 6 months before requiring reapplication.
In regard to carnauba waxes, there are several different qualities available depending on the look you are after, how much time you have to spend on the car and how deep your wallet is. Initially, you can split it down the middle by saying that there are "cleaner waxes" and "pure waxes". The cleaner waxes are a one step product gearded toward those that may have limited time or interest in detailing their car. Cleaner waxes both polish and wax at the same time - they do contain abrasives. In my experience they do not produce the same results as a separate polish and wax, but that is up to the individual. Many different manufacturers produce cleaner waxes that are readily available, such as Eagle One, Zymol, Meguiar's, etc.
Then there are the "pure waxes", and you will find varying grades of quality within this grouping as well. Typically speaking, waxes lack durability. As I stated in my previous post, waxes require reapplication (depending on the wax and the conditions that the car sees) on a regular basis. Carnauba in it's natural form is extremely hard, and is therefore processed with oils in order to soften it for automotive use. Some carnauba waxes are yellow, others are white. The white waxes are more refined than the yellow, and often cost more as well. A "pure" carnauba wax contains absolutely no abrasives, it will only add depth and richness to your finish. I don't use any over-the-counter type waxes as I find them unacceptable in their performance, but the Meguiar's product that you mention (yellow #26) is one that is usually well spoken of. The #26 is what is called a "hybrid" as it contains both a polymer and carnauba. It is not inherently bad, just how Meguiar's chooses to manufacture that product.
You ask about using a separate polish with the #26....the #26 does not contain an abrasive, so depending on what you are trying to address on your finish, you may need to use a polish first. I am not one for "combination" products (a polish/wax combination). I have always felt that superior results are achieved by using single purpose products. On my car I use a polymer (Klasse Sealant Glaze) follwed by a quality white carnauba wax (Pinnacle Souveran), but that is just my preference. One Grand Blitz wax is also an example of a quality carnauba wax (and it's alot easier on your wallet than the Pinnacle Souveran).
I don't know what the condition of your paint is, so whether you require a polish first, is up to your discretion. Just keep in mind that proper paint prep will always play a significant role in the end result.
I hope that this has been somewhat helpful to you.
FORGOT TO MENTION: If you go the polymer route (either Klasse or Meguiar's sealant) there is nothing wrong with topping the sealant with a "pure" carnauba wax. Typically speaking, a sealant adds reflectivity while a wax adds depth and richness. So depending on the "look" that you prefer, you may want to use both. Build up your layers of sealant until you are pleased, and then add the wax. Just remember that a sealant will not bond to wax. There are mixed reviews about topping Zaino with a wax, and Sal Zaino does not recommend it.
