There are always the issues of build quality and long-term durability with daily use. A $$$ heat gun will usually stand up to regular use and rough treatment better than a $$ heat gun. Both are about the technology same inside: resistance wire with a fan blowing through a metal tube. Resistance wire is cheap, metal is cheap, injection-molded plastic is cheap at production scale. There's nothing too expensive in a basic soldering iron, either. HF is in business catering to people who will accept lesser quality for a lower price, for tools that will last a while with occasional, hobbyist use. Hair dryers and clothes irons have to be made pretty for women to want to purchase
plus packaging has to be pretty, and advertising must be paid for as well.
The main danger with soldering is heat, heat and more heat. This is a relatively large part. Touching any part of it at over 70 degrees C or so is going to hurt. You're talking hundreds of degrees C at the solder joint, and the metal plate will spread heat away from the solder joint pretty well. It is possible that a clothes iron on high could prevent it from losing enough heat, so you could melt the solder joint with an iron. A clothes iron will also make a handy flat surface to hold the plate for you. The way to find out is to try.
A 1500w heat gun is a pretty heavy load on the mains, but most modern homes will be fine to run that as well as other appliances. Unless you are in a building that is a fire hazard due to ancient and poor wiring, the worst that will happen is the mains voltage will droop some, and then circuit breakers will trip, when too-high powered devices are in use.
Most paints are full of volatile chemicals that will be driven off by normal air temperature. Higher temperatures will often speed drying times but are not necessarily required. The easiest way to get a bad paint job is to use paint that will not adhere to the material being painted, and the next-easiest way is to try using a single or two thick coats vs. lots of thin coats. Painting technique is an art in itself, and you will find plenty of videos on Youtube showing proper form to prevent things like runs/drips.
Differential expansion might help remove some things, but PCBs (made of fiberglass reinforced plastics) are pretty stable, and if anything the metal will possibly expand faster, but not so much it interferes with getting the pieces apart.
