Don't worry about using a quality soap (Meguiars Gold Class) washing the top. It is designed not to strip coating and waxes away. There is nothing in that ( I use it too) that can harm the top. (Don't use ArmorAll on anything especially vinyl/plastic on the interior as well)
You don't need the fancy brush. I use a soft pad with microfiber "feelers" on one side and a soft scrubber type fabric on the other. (Wal Mart has them) That does the trick unless a pine tree dripped on it. Then I use a microfiber towel with some sap remover but that is exceedingly rare for me.

I buy the Raggtopp Protectant and use that every other wash or so. My car is always garaged so that helps with the UV exposure.

 

I tried the Surf City Garage Top End product and I liked the results. I didn't use a brush either as cosmomiller mentioned. I wasn't going to pay $20 for a decent brush that got good reviews on Amazon. The rough side of a microfiber did the trick for cleaning and then I just misted another coat to finish blending with the fine side of the towel.