1995 Pontiac Grand Am White smoke coming from engine oil co

Hi I'm having a couple of issues with my car I'm just wondering how I can fix it cause there are so many different options that I can try. First of all I'll tell you all of the symptoms that I'm having.

My antifreeze leaks from somewhere around the middle of the car horizontally when my car is not being used that is the only time it leaks, because of this leaking my antifreeze storage tank has white smoke coming out of it I guess due to the lack of antifreeze. When this happened before I would just refill the tank with antifreeze and the white smoke would go away, recently I put in a alternator after putting this in I had the issue with the white smoke again except now my whole engine and muffler have white smoke coming out of it. While I'm driving the car white smoke comes out of the exhaust but not engine then when I come to a stop and the car idles white smoke comes out from my hood. I tried filling the tank with antifreeze but it does nothing to fix the smoke problem. Also my heater does not heat it will work sometimes after I have the rear defogger on. I noticed a light squeeling noise coming from the water pump area but I notice no leaking around that area I also checked my upper radiator hose and it doesn't heat up so it might also be my thermostat. I also accidentally added 10W40 oil to my car instead of 10W30 will that cause any smoke problems? My engine or exhaust never had white smoke or steam coming out of them until after I replaced my alternator. Can you help me out in anyway please. I'd greatly appreciate it.