The information in the Pestal 101 thread pretty much explains everything.
30 cards is optimal for the highest chance at getting a turn 1 Pest and, ideally, a turn 3 Fractal. Dark Pendulums rather than Obsidian Towers help fuel your
quanta for those fast Fractals, while your Pests will keep bringing in the
.
Steals are fantastic, but gearing your build towards fast quanta lockdown can mean they're often unnecessary. Play around with the deck, and see what suits you best.
Great work on the deck, regardless - nice to see you experimenting with the Devourer/Fractal combo, Devtal is typically regarded as one of the most powerful competitive PVP decks around. Like Manuel said, welcome to the forums, and feel free to ask any time if you have other questions!