I used just the bolts for the horizontal stabiliser on my first one. They worked fine. I'm not sure how long they will work until things get a little loose if you continually remove and replace the stabiliser though.
On the one I have now, I have eopxied the stab in place - as well as using the bolts.

I would strongly recommend replacing the 2-56 rods with 4-40 ones. The 2-56 are fine for sport flying but if you use any 3d type throws they are not up to the job.
I use 4-40 rod with some CF tubing epoxied over it for mine.

The stock Horns are Ok to use (They are genuine Great Planes ones). I replaced mine as a matter of habit because I prefer to use MK's on everything but think it may have been a bit of overkill.