Renderotica

It looks like a couple issues you have here 

First on the black guy did you run the copy materials script on dicktator cause the textures don't seem to match.

Second on the shells it looks like there may be two problems

First it appears the shell offset on both figures are off (this is why it appears the underlying skin texture is apparently poking through the shell) there is a mesh offset setting on the shells that you can adjust.

Second did you apply any of the shell textures to the shells, the shells shouldn't be white usually. they load in white, but after you apply the shell textures they should match the shell texture you used (I believe in most cases the shells are set to color the labia minora and anus on Golden Palace and the glans and anus on dicktator as well as adding veins through displacement if you use the veins on the shell surface)

If you have multiple shells on a figure in the scene there are shell fix scripts to run, that will take care of the white being added by and to the other shells, just select a shell in the scene tab, click on the shell fix, and then repeat on the other shells till everything looks right.

On the missing files follow the paths the errors show to verify the files are there, then check to see what discrepancies there are between where the files say they should be and where they were installed and fix them to match to where they should be. There has been some issues of late with sometimes when certain extraction programs are used it seems to be adding or deleting spaces in the files and folder names, and if it is different than what the files say and where they are looking it will throw the errors you are seeing in Daz Studio.