Most of the time a Kerfed port will not make a massive alteration to the sound you actually hear. It can but the likely hood is very small. They do look better though.
As for doing the enclosure yourself, there are several vendors and members here that do designs but most of us charge for those but they are easy to follow and will normally yield an overall great product assuming your craftsmanship is on par with the design.
As for you ideas on painting and logos. Here are few pointers for you to consider when painting and such.
1. Sand away any imperfections from building then enclosure.
2. Bondo all seems to hide them and make the enclosure..well...seemless..
3. A good way to do the logo is to first primor the whole enclosure. Then pick out the area you want the logo to be and paint a larger area then the logo will be with blue paint. Lay down a vinyl graphic decal of the logo/design you want blue. Once you have done that paint the whole enclosure black with the decal in place. Give the paint time to set and then pull the graphic off which should reveal a blue logo if done correctly. Then clear it and your done.