If you convert your current triple chainset to single you might have to change the chainring bolts also (I've had to on 2 bikes).
When removing inner and outer and fitting a bash-guard ring, you might need longer/deeper bolts because bash-guards are often thicker at the drilled fixing lugs than a chainring.
When removing inner and middle, and leaving outer ring, you'll probably need thinner bolts to take up the slack of the missing middle ring width.
If you're not sure which bolts I mean have a look here (commercial link but good example images): http://www.chainreactioncycles.com/Mobile/MobileCategories.aspx?CategoryID=4
2p - in my opinion you will get regular chain drop on all but the smoothest trails if you don't get a bash/guide combo as already suggested, or double roller also suggested. Worth every penny :)