Hi Rani,
welcome to the forum, let me try to answers you questions.
Test prints.
There is a function in QU call "Test Strips" which does exactly what you require. It's access in the Page Editor, second icon from right below page preview on main screen. Here is a copy of an earlier post on the same subject.
http://ddisoftware.com/tech/articles/april-2010-understanding-your-photo-printer/msg12085/#msg12085
"Test Strips - Before printing large prints and committing large amounts of paper, printing a small section of the large print can be helpful for the purpose of judging detail, sharpness, and color.  There is a "Test strip" function on the full page editor that will allow you to create a small, proportional print that contains a piece of the larger print.  From the main window in Qimage, start by adding the photo you wish to print at the desired final size (20x30 inches for example).  Then click the "Edit Page" button below the preview page, select the print on the page, click the "Cropping" button on the right and the "Test strip" button will be visible under the small crop window.  The test strip button can be used in any of the following ways:

You may repeatedly click the test strip button to make your test strip progressively smaller until you have a size as small as you like.
You may click the test strip button once and then change the size of the print manually using the sizing functions on the main window.  Once the test strip button is clicked, that print remains a test strip which will conform to a piece of the original size print until you remove the print crop or manually move the crop zoom lever in the page editor.  You could, for example, start with a 20x30 inch print, click the test strip button, and then choose a new size of 4x6.  Since the print has been identified as a test strip, the 4x6 print will be a 4x6 portion of the 20x30 print!  The area of the 20x30 print shown in the 4x6 can be adjusted by simply dragging the crop in the page editor or using the high precision cropping tool in the page editor.
You may select a smaller paper size (4x6 for example) and add your large print to the queue, specifying that it is OK to create a poster larger than one page.  Then simply click the test strip button in the page editor once and the test strip will automatically be resized to the size of your (smaller) paper.  The crop can then be moved manually to any part of the print using the cropping tool in the page editor.
Note that while left clicking on the test strip button will make the test strip smaller, right clicking or Ctrl-clicking on the test strip button will make the test strip larger"

If this is not all clear to you, come back and ask for clarification.

Soft Proof
QU does not indicate out of gamma colour. Not sure why that is necessary as the colour management conversion will convert the image to be within the printer gamut according to your rendering intent choice. The gamut of most images will be way different from a printer gamut. Be very careful relying on soft proof; there are TWO conversions taking place, image to printer and then printer to monitor, so you need very accurate profiles for both! A test print is a much better guide.

Image Colour Space
First, QU is an 8 bit application and will convert an image to 8 bit for printing. Read this article as to why.
http://ddisoftware.com/tech/articles/september-2009-digital-photography-reality-check-308/
All inkjet printers have a gamut much less than Adobe RGB, never mind prophoto! See the above article on that too.
Adobe RGB colour space will be fine I'm sure 

A a new user of QU, I recommend you look at the QU Learning Videos here:
http://www.ddisoftware.com/qimage-u/learn.htm
and read the techie stuff on the web site:
http://www.ddisoftware.com/qimage-u/technology.htm

Terry

All works for me except for the step after selecting the "test print" button.  When I return to the main (Left side) page I am only able to crop dimensions proportionately.  I want a true sized test strip with  maybe only ONE dimension reduced,  say a 7 inch by 24 inch area selected from a 18 X 24 inch image, or a 7 X 15 inch area for example.  I will combine this with a prop reduced image one one sheet for the client proof.   Simply am never able to do except to a crop in PS then save and handle as a separate image in Q.