Lots of airline staff and experienced fliers in YYZ. The terminals are well signed and laid out as well.

I'm sitting here now after not having flown for 22 months due to covid. Had no issues clearing the CBSA and customs, as well as changing terminals. A little rusty as you'd expect, but I'm back at home now.

You'll be fine. Canadians are helpful to a fault. Just ask anyone if you're having trouble here.

Do you have an impaired driving charge on your record, or another criminal charge however ? You won't be admitted to the country if you do. Also, as previously mentioned, a wrongly worded statement to the CBSA about visiting a girlfriend here will perhaps create denial of entry issues for you too.