Ref. your smoke generation - just how old is the fuel? Also any idea how the Previous owner treated the mix? When I got my Boat with the Yam the guy said (and I paraphrase slightly) "I accurately mix the oil, then throw in a cupfull for good measure!
Have a search for mix ratios - I posted a thing to calculate how much oil to "preload" an empty tank with. Lots of people used to "add a but more just so it doesn't seize", resulting in some remarkably oily mixtures. Also might be worth changing the plugs unless you know they are new.
If it still smokes after a decent mix has passed through the carbs, you may need to adjust the idle mix. Mind you. if it's premix and hasn't stretched it's legs for a while there's going t obe an excess of oil hanging around in the engine anyway. Mine won't run for more than about 5 mins at idle without starting to cough.
Ref. the choke, if you don't have a separate choke switch and it's a Suzi control box, push the key in while you turn it. You (should) hear the solenoid click in the engine as you push the key.