~15% of annual revenue appears average, though that number can vary depending on the company's priorities (e.g., Avigilon is ~10% up from 5% a few years ago). Here's Milestone's numbers including R&D from a few years ago.
As for staff, I would guess Genetec and Milestone have ~100 people in R&D (including software development, QA, tech support, etc.). This is based on my understanding that both companies have ~500 employees (Genetec more, Milestone maybe less). That said, Milestone has been expanding their development teams in Eastern Europe, with a lower cost base, so perhaps they have more. Not sure.
What are you looking to decide or evaluate with those numbers?