Removing a wall???

There is a small 4 ft. wall between my kitchen and sun room that I would like to take down. I have taken off all sheetrock and the wall is now just studs. It runs parallel to the joists so I am guessing it is not load bearing. Here are my questions:

1) How can I be sure that it is not load-bearing?

2) If it is, can I run a header spanning the current opening and the wall length (total of 10ft.)???

3) If I use a header, how can I support the load while I work on installing a new header? And should I use 2x8's or 2x10's?

If you can help, I would greatly appreciate it.

 

it can't hurt to use 2 X 10s. Build a temporary wall while your installing the header.

 

If it is only 4ft long, coming off a wall, and running parallel to the ceiling joists - then it is more than likely not load bearing.