everything iv read says thy hve fast metabolisms, so i wouldent worry about it a decent lump is alright just make sure the lump isnt to big. i have to get my girl on rats, id reccomend u do that soon as it will be easier iv never read the 10-12 meals a year tho, i use a 5day feeding plan 7 at the most. as babys they need the food, but can be slown down at an older age to once every two weeks depending on the rat size they get up to.
and as for the heat, the best and easiest way to put it IMO is they know what they want better then we do, snakes may not be the smartest but if givin the proper temp gradient (which it sounds like u have) they will do whats best for them.
on a side note, hows the attitide on yours? cause my girl is nuts! i have a female coastal whos a youngin maby a foot long if that and man is she quick! bites first and sees what shes chewin on second.. lol cant wait till she grows out of it