When will I have to go thru customs and immigration on this plane trip?

Crazy, but the cheapest way is USA to Canada to Iceland to Amsterdam to Abu Dhabi to my final destination of Kuwait. I will not be visiting any of those countries, just staying in the airport changing planes except AbuDhabi I stay on the same plane that goes on to Kuwait. I'm a US citizen. Thanks- never had such a crazy trip before, but need to do it cheap! Will I have to claim my luggage and go thru all that mess in every country or can I check it thru when I get on the 1st plane in the USA and then pick it up and do all that in Kuwait?

It all depends on how it was booked and who you are travelling with. Some airlines have interline agreements for baggage, but expect to be aware of your travel plans on the partner airline, if it's the same carrier all the way, which I do doubt by your routing, then it should be smooth, I would check if you need transit visas for any location you will need to pass through customs before rechecking for your next flight.

I'm a US citizen.
Has nothing to do with the answer.
ALL passengers when arriving in some country may need to pass a passport control point and a customs inspection between flights.

Some Airports for SOME flight connections allow you to stay in part of the Airport in a secure area to just change planes. It is for some connections not every possible flight combination you can dream up.

It appears you discovered some of the low cost Airlines. The cheap seat comes with the extra expense of TIME

You probably can't check your bag all the way without any passport or customs inspection.
Most likely a check by Canada Customs before you can get to your flight to Iceland.
EVERY AIRLINE does not have through luggage procedure with every other Airline on the planet. SOME DO
have this with some partners.

You can verify your details about needing to claim during your journey at the first check in place.

For a more specific answer the Airline that you are on for each flight segment matters,

The Airline may have the next flight from the secure International transfer area or it is not. It is not the same for every possible connection.

As you have some long flights its is prudent not to push the limits down to the minute. Many things can delay you an hour or two at each stop. Before your flight departs. Things like weather happens to mess up your to short connection time. That you get a meal or maybe a hotel night while you wait for an available seat might mean a Customs inspection to use the hotel.

Some luck out with short connection times between flights. Sometime one late departure messes up the rest of your travel plans.In particular your first flight to Toronto.

Are you using Porter Airlines to Toronto? It uses a different Airport than the flights to Iceland.

allow time to get from one Airport to the next a Passport/Customs check and then security check for outbound flight. YOU MOVE your luggage between Airports.

Usually not in Amsterdam.
Allow time for the inspections. The Airline does not give you a free next flight if you are delayed by inspection procedures.

If you want a more specific answer than give more specific details on Airline used for each segment.

WOW air flights do not involve any interline cooperation with other airlines. This means that you will have to treat flights with other airlines as if they are the first flight in your journey.

HINT you claim your luggage and recheck it Expect a check in Canada Iceland and Kuwait City.

The inspector decides if it is a short minor check most pass in a minute or less or an in depth search that can take hours.

Yes, you will.
Canada requires international transit passengers to go through an abbreviated customs and immigrations.
Iceland and the Netherlands are both Schengen countries. Your flight between those two countries will be 'domestic' so you will do customs and immigrations in Iceland.
Of course, you will also go through it in Kuwait.

However, you shouldn't have to claim your luggage on any of those stops.

I say BS that that is the cheapest route. I looked on kayak from Chicago to kuwait city, with just a single stop in Frankfurt Germany for under $650 flying Lufthansa the whole way. That is round trip flight.