If you can use the middle ring off your triple, or even if it was a road compact double on there, the inner can be used without it looking too gash. I’ll second that KMC 610HX chain – they’re so easy to join, and if you need it, Charlie the Bikemonger does half links in 3/32 as well as 1/8th inch, though you shouldn’t need it as you’ve got the conversion kit with the tensioner. There’s not much else to it really 32:16 will be fine for most off road stuff (but you’ll have to push up some of the hills). Bigger front ring (or if you can find one, a smaller cog) will be needed to stop you spinning out on the road.
Getting your chain line striaght is important, but you should have a load of spacers in the pack – you’ll need to use the lockring off your cassette to hold the spacers and cog on. Once you’ve got it in position, look down the length of the chain from the rear and try to get it as central as possible. You’ll be able to run the doofer pushing up or down on the chain, and I’m sure if you search on here, there’s plenty of posts on which is the best way to do that.
You’ll have fun – go for it.