Are you referring to when you're working in the program, or when you render out a final clip?
Is the footage you're working with interlaced or progressive?
The way the program renders depends on your project settings.
If you've created a progressive project, then it'll just work with full res frames throughout.
If you've created an interlaced project, it'll split each frame into its 2 separate fields while you work on it. When you render out, it will then re-interlace the fields back together to form the frames.
I'm not entirely clear on where the problem is?
Regarding the in and out frames, the render menu does have options for those. You can also set them on the timeline.
Check out the render tutorial for more info:http://fxhome.com/support/vidtutes/?t=7&f=%2Bcat%3A6&cat=6