As you guys know i just bought a 02 Mustang and the winter is about to come. im gunna try n get this car running top notch before the snow and the cold weather comes here in canada.. My motors starting to make a tick sometimes when its cold , and the rpms fluxerate somewhat when im idleing and its just not running smoothly.. got a few questions all your guys answers / openions will be greatly apprechiated

2002 Mustang 3.8L V6 , Cold Air intake , Flow master exhaust , (( 244k )) 5 Speed

1)What oil should i be running now ? 5W:30 Mobil1 High Mileage with a motocraft filter?
2)What Plugs do these 99-04 Mustangs Like the most or go back to manufacturer spec? and should i replace the wires while im at it
3) I got 4 Winter tires not studded but there in very good condition Should i be fine if i put them on and throw a couple sand bags in the trunk. we usually get no more than 25Cms of snow during a snow fall i wouldnt be driving it if the roads are terribly bad.