Every contractor I've worked with has taken 50% up front and 50% when the job is finished. This is normal. One thing I would recommend is you vet your contractor thoroughly--check reviews, make sure they have a legitimate website, testimonials etc...
CCDC contracts are ubiquitous in the construction industry. They are used for all manner of different project types and sizes, so much so that familiarity with these documents is almost becoming required to do business in Ontario's construction industry. There are currently around 14 types of CCDC format contracts.
The CCA specifically handles documents affecting the contractor to sub-contractor relationships while the CCDC documents typically handle contractor to owner relationships. Contracts Covered: CCA 1.