Dear Trev
I have found the easiest way to paint rabbits is with a brush as spraying can be a little messy not to mention time consuming, by the time you mask off the areas you dont wish to paint
Down here in New Zealand it's a railway station and trains travel on tracks (no road trains) the trains are pulled by locomotives and pushed by shunters. when you ballast track remember to keep the ballast just below the sleeper height around moving parts everything should still work after the glueing process. I also use a brush to move the ballast around after first placing with a teaspoon, it is surprising how little it takes to go a long way,and even more surprising how long it takes to do the smallest amount.
cheers for now
dave