You don't really need to take everything apart to clean it. Just rinse the coil head in hot running water, shake it dry and then dry burn if you want. I'd rinse mine every 2-4 take fills (less when using clear juices, more when using darker liquid) and dry burn every 3-4 days or so.
Silica cannot burn so any burnt taste remaining from the coil head after cleaning is residual juice gunk on the coils - or it's a dry hit. I suppose you might have scorched the rubber grommet in the bottom of the coil head - if you have, the burnt taste will never go away and the only option is to replace the head.
I've never had to soak anything before, but I can see how it would be handy to remove any strong flavors from the coils.
I've also used an Igo-L RDA on a spinner for a short time with no problems. You do need a way to check resistance (I usually used it around 1.6-1.8 ohms) and make sure there are no shorts before mounting it on your battery. A multimeter or a mod that has a resistance reader is a minimum requirement. Of course I know using a Spinner is not recommended for an RDA but that is mainly because they have such a low amp rating that it's easy to get yourself into trouble over-stressing the battery. This can lead to serious damage to the battery or to you.
As for cotton, yes, for me it gives a much cleaner tasting vape. Plus it's easy to change a wick out.