Well, for what it's worth, a 29G would probably be okay for the barbs, but the pleco...? Hard to say. :-\ See, I have one too, and common plecos get HUGE, some up to a foot long. They have a pretty big bio load too, so it's going to eventually outgrow a 29G.
If it's a bristlenose or clown pleco, you could get away with it.
For test kits? I use API Ammonia, Nitrite and Nitrate liquid test kits. I recommend against the paper/strip tests since they tend to have accuracy issues. Each kit was about 8 dollars, though I've seen all three together for about 20.
Jump starting the cycling process is a loaded question... A lot of different things claim to add bacteria that speed up your cycling process. I use StressZyme, myself, which isn't bacteria that needs to grow for your biological filter. Instead, it's bacteria that take gunk in your gravel and turn it INTO ammonia. BioSpira seems to be the only thing that speeds up the cycle, but I've never used it so I can only go on what I've heard.
lol
