My acquisition of French has been through immersion, since moving to Île-de-France Region in 2010. Not shy, and needing to communicate, my first discovery was that simply speaking English with as strong a French accent as I could muster went a long way to being understood.
bis ter quater quinquies sexies septies octies - are used to add in extra house numbers in a street.
Grammar is stricter in French
Bertrand Boutin offers an excellent page on "l'article" .