I use the coat king and I don't think it ruins the coat any more than clippers, but it gives a nice natural look. I wouldn't worry too much if you are not showing, the coat king will tidy him up no end. I got the 26 blade from dezynadog, it is just around the corner from me and that was the one they recomended after looking at him. They have a website.
I bought thinning scissors from pets at home, and everywhere else like the ears, and legs I hack away with them and then I do his feet and feathers with straight scissors trying to follow advice on here. I have never groomed a dog before, am not at all arty or creative but do you know what, I think he looks great and so do other dog walkers. I actually prefer the way he looks to my friends cocker who pays £40 a go! It is because i can do him just as I like without any drastic changes, just a tidy up here and there.