Hi. My rule of thumb is that 1 lb of honey dissolved to make 1 gallon of must (the mead before you pitch your yeast) will have a specific gravity of 1.040. So, 2 lbs will have a gravity in one gallon, of 1.080 and 2.5 lbs will be about 1.100. Obviously, I have no idea of what recipes you have but IMO you want to have about 2.5 - 3lbs of honey per gallon to have enough flavor from the honey. If you want a mead with a higher ABV (because fermented dry 1.100 will give you a mead of about 13 %) then you want to have added more honey per gallon. Higher ABVs may need to finish with more residual sugar to balance the alcohol and that may mean you need to step feed the additional quantities honey so that the yeast can still thrive rather than succumb to alcohol poisoning or to their inability to maintain osmosis when the concentrations of sugar are too high...
As to heating honey, I cannot speak for others in this forum, but heating honey has fallen out of favor in recent years. Heat destroys volatile molecules that provide flavor and aroma and even raw honey for adults is viewed as safe. Your yeast will take care of any wild yeast hanging around on the surface of the honey, although if you are at all concerned you might add one Campden tab per gallon after diluting your honey and 24 hours before you pitch the yeast. The Capmden tabs produce SO2 and the SO2 acts like an antibiotic to kill yeast, fungi, bacteria and the like that may be in fruit or in this case , honey. (Sulpha drugs I believe were/still are often used to treat bacterial infections in animals) .
