Guns will be a problem to import as an individual. Leave those, bring the rest. Gear, clothing, magazines, optics, etc. it's all OK.
Don't worry about getting age verified till you're here. You'll be in Toronto; one of the hubs in Canada for airsoft. You'll be able to go to a bricks and mortar store, get the info checked off and buy another WE M4 off the shelf.
Then after that you can carry on sussing out the local scene.
Airsoft, where nothing is hurt but feelings.