A: If you have a manufactured home with a Miller CMF80 oil fired furnace, you would typically replace it with the new version of the same thing. That way it would line up with the duct work that is below the floor. I am not familiar with the PG suffix you reference. But then again there Nordyne has made many variations of the CMF 80, branded Miller over the last few decades.
A: This is a fairly standard installation. Any heating specialist can install this unit.
A: Sorry but these questions are routed to the supplier’s technical people and not to The Home Depot. Thus I am not familiar enough with their install programs to give you definitive answer as the install programs vary greatly throughout the country. You may want to call you your local store or give the Home Depot’s installation department a call at 855 752 3352
A: Sorry but installation costs vary so widely throughout the country I could not even give you an educated guess. I would suggest reaching out to your oil supplier.
A: Coleman is a brand name that has been licensed out to a number of different companies over the years. I am unfamiliar with the model you are referring to. Therefore I am unable to give you a definitive answer. Definitively determining it this or any other appliance is a suitable or best replacement you need to be in on site. I would suggest you reach out to a qualified, licensed, oil technician in your area. To achieve this you may want to contact the company from which you purchase your fuel. Often they have qualified people on staff to service their fuel customers equipment.