Canoeing is absolutely safe because most of the waterways except for a few larger ones are only knee-deep.
Mosquitoes and horse-flies can be pretty annoying in wet summers and summers following mild winters. However, repellents will help.
talk
Most people only speak German at least the standard variation without major accents. Some younger people understand and speak English, some older people might still remember a few words of Russian. Some people may still speak Low Geman dialect and Sorbian is still spoken in the south of Brandenburg.