[mikesbike]

The zooms having "focus breathing" which involves a reduction in FL from that which has been set on the lens when moving closer to the subject, generally is a phenomenon peculiar to many that have an internal-focus design mechanism. I don't think the DA 18-55mm kit lens has this type of design, so it would be a non-issue.

The idea of "trying out" a particular FL in advance of buying a prime of that FL is not a bad idea. The simplest way is set the lens to the approximate of that FL, say 35mm, and go around taking shots of this and that scene using that setting. It would be close enough to get a good idea of what to expect. If wanting to be exact instead of approximate, the suggestion of using test shots to home in on exactly 35mm via the info display should do it.