Hello Brisea and Welcome to ECF,
The reason some people use either a cotton or silica wick inside their mesh is for better or faster wicking. Some say it also keeps their juice clean, sometimes when a wick has been over oxidised or just ages over time it tends to make the juice darker. You can also wrap cotton around your mesh wick and that helps prevent hotspots, can improve wicking and can be quite rewarding if you get frustrated with hotspots as a newbie.
Not many people Vape at 20 watts, firstly it kills your batteries and secondly you can achieve the same vape with less watts. Most people vape between anywhere between 5 to 10 watts. Just because a device offers you 20 watts doesn't mean you have to use it at 20 watts.
It really isn't rocket science to roll a wick, once you've made the wick, always roll from the center > out and always in the same direction. In other words don't roll it back and forth. Make sure the edge of your mesh is either turned in or that there are no little threads touching the coil, those little threads love wrecking havoc and can make many hotspots, you can also burn them off with a lighter before you roll the wick.
There is no "this is the perfect wick for everyone", some like to use more mesh for stiff solid wicks, whilst others prefer less mesh more pliable wicks. Some like 325#, some 400#, some 500# and some 600# SS, it's not all the same and only experimenting will tell you what you like best. It also depends if you are averse to tilting your mod when you vape.
You still need to maintain your coil and wick, irrespective of what it's made of. Coils gunk up just as fast as any other method, depending on amount of juice vaped and type of juice used, mesh clogs up too. Yes, the mesh is very long lasting, but it does degrade over time.
@ WingmanJudas: There are No Potential Dangers to Silica!!! Where did you read this mis-information? Please provide the source.