Welcome to the forum!

If you haven't already done so, check out this thread:

Knife of the Week Model 5

It's 28 pages long with lots of photos and info.

As for your questions:

1- If the knife is going to just sit on your desk, then get whichever sheath you think looks best. Randall recommends that you don't store the knife in the sheath. If you plan to anyway, you might want to consider getting stainless steel.

2- If I were the Captain, I would say, "No, it's not a Model 5. It's a Model 28." Although he would probably say it with more personality!

3- Yes, it's close. The Model 1 All Purpose Fighting Knife was the basis for the Model 5 Camp and Trail. I think of the Model 5 as the All Purpose Knife. The top of the blade in front of the hilt is straight (unlike the Model 1) which makes it suitable for thumb notches, which is a feature that I like. Thumb notches are standard on the Model 5. And the Model 1 has a sharpened top edge.

4- The grind on the Combat Companion is very different from the Model 5. At least, it is to the practiced eye. Check out this thread:

Knife of the Week Combat Companion

5- No. Not any handle on a Model 5 will have an exposed tang.

6- For a desk knife, one's as good as the other. Get whichever one looks best to you. For a field knife I prefer the Model 5.

One thing you should consider is the style of hilt to order. The Model 5 is available with a rounded hilt or a squared one. Again, it's just a matter of which one looks best to you. Some people don't like the pointy edges of the square hilt when handling the knife.

Also, consider getting aluminum spacers with the NS hilt. They count as an extra option but they look really nice.

Deciding on which model and options to get is part of the fun of collecting Randall knives. Enjoy the process!

Rick