Ok... since your son is getting married and is (I assume) an adult, I’m not sure why this falls to you and his father.
Your questions cannot be answered without a lot more information, and frankly the best source of information will be Immigration Canada. They have a pretty comprehensive website (
www.cic.gc.ca)
In general, your son can enter and leave the country like any other American - on a tourist Visa - for several months and at the disccression of the immigration officer. To stay there permanently he will need another Visa. What type depends on what he will be doing there. If he is young, educated, has assets, certain professional training and is married to a Canadian he will qualify for a work visa rather easily. Some professional fields are easier than others.
Once he has moved to Canada he can begin the process of becoming a permanent resident, which is the first step towards citizenship (should he want do go down that path) and - again - the steps involved depend on the providence and what kind of visa he has.
Health insurance depends on the province. Despite the catch-all phrase “Canadian Health Insurance” there is no single Canadian plan - rather each province has their own and their own rules for when non-citizens are eligible (and when citizens are not). So check with the province. Typically he will need to have his own private insurance until he qualifies for provincial health insurance, which can take anywhere from a few weeks to a year or more depending on his job and visa status.
FOr investing in Canada you might want to read up on the Canadian Couch Potato - there’s a wealth of information there. While the options are a bit more limiting than in the US, in general the system is pretty similar. You can also check out the Canada tab on the Investment Order (it has its own Sticky). Like our Roth and regular IRAs, Canadians have RRSP and TFSP options, each of which has their own advantages and disadvantages, but both are tax-advantaged accounts. What he should invest in depends on things like his income, investing goals etc.