RE: bulking and weight gain
this will be quite hard to explain but hopefully i can do it.
well my understanding would be (this is nothing scientific) when you workout your body needs extra cals to grow, but this amount of cals will be different for each person for a number of different reason, genetics, training, supplments etc.
so you want to know if by eating 500cals over maintance you will gain more lean mass then if you eat 200cals over maintance, i would say yes but this has to be offset by what fat you will gain at the same time.
so for example if you eat 100 cals over maintance 90% might go to lbm where as 10% might go to fat, and i would guess this would stay pretty steady upto a point(this is where i guess it will vary from person to person), lets just say 300cals, so 270cals would turn to lbm and 30 cals would turn to fat, then it would be a case of diminishing returns.
so it might look something like this
upto 300cals 90% turns to lbm
then the next 100 cals 80% turns to lbm
next 100 cals 70% turns to lbm
next 100 cals 60% turns to lbm
so 700cals over maintance might look like this 530cals turn to lbm and 170cals turn to fat.
also i think the diminshing returns would actually be a bit more drastic than what i put above, so once you have reached your point where most cals turn to lbm then i guess it would actually drop off to some thing like a 50/50 split lbm/fat and then gradually get worse.