I sincerely hope you didnt want a serious, objective, answer.
In those that dont have the tendacy to over smoke the stuff, cannabis is a pretty darn safe and non-addictive drug. Only around 6% of people who try it, go onto use it regularly. Compared that with 90% with alcohol or around 95% with nicotine, cocaine, or heroin. Admitedly its fairly habitual for that 6%, but I think on the basis of measures of general addiction, withdrawl and so forth, it could probably be considered less harmful and less addictive than caffiene, and thats what some studies have said (not saying its true, or not, but it is low on addiction scales)
Its estrogenic effects are minimal compared with its cousin hops, found in beer, for which its estrogenic effects are so strong it causes contact dermatitis. So if you drink beer, cannabis is the least of your worries, estrogen wise.
I cannot comment on its effect on leptin however.
For hunger induction, nasea reduction, nerve pain or smooth muscle relaxation, cannabis is pretty unparalleled. It also releases melatonin (which may be too much if it drains your gland from overusing the stuff and why stoners dont dream), and probably has other anti-oxidant effects.
Of course it does have side effects, such as (until cessation of use) short term memory loss, lowering of sperm motility, some increased risk of psychosis (not as much as with alcohol, and certainly no where near strong stimulant drugs) and, as well some amotivational syndrome in those that over use it. I am not aware of any proven long term effect that doesn't resolve with cessation tho (doesnt mean there isnt any of course).
I cant really answer your question on leptin, and as far as estrogen goes yes its true, but its not as bad as beer in this regard (or almost all regards). But I just thought id try to post up something objective, coming from someone who has partaken, done research, knows neuropshychology and no longer touches the stuff.
It definately increases hunger. And that probably is useful for bulking, but id stay away from very regular usage of any drug if it can be avoided. Messes with your bodies balances.
There are cannabinoids in chocolate (in trace levels). Chocomine has some pretty decent stimulants in it too. I am not sure its effective for appetite increase as well, but can be used to boost a workout. Or you could try one of the bulking formulaes containing echinacea isolates. But, like chocamine, one cant be sure if those particular cannibinoids actually stimulate hunger effectively. And again, id recommend against very regular usage of any drug, if it can be avoided. The body is a complicated mysterious beast after all.
As a side note, endocannibinoids are strongly implicated in the runners high, moreso than endorphins. Supplementing with archanoic acid (sp?) boosted endurance excercise by 30% duration. Unfortunately AA is also pro-inflammatory, and pot itself has too much in the way of direct cb1 agonism to be useful for endurance gains. But its worth noting that cannabinoids are most likely involved in endurance, and particular kinds of cannabinoids, particularly the endo kinds may give functional boosts to performance (probably the more selective kinds, as opposed to broad acting marijuana).
Endocannabinoids themselves are also involved in pregnancy and injury. They serve as a kind of physical stress adaptor. This, and the effect on melatonin, is probably a good motivation to not to use pot too regularly (In addition to habituation in those minorities that find themselves in that situation)
As far as the strain talk goes, there is some chemical truth to this. Strains higher in thc, but lower in cbd are more stimulating. But then again those lower in thc and higher in cbd are less of psychosis risk factor. There are thousands of cannabinoids in pot, and it is often said in science that pot is 50% stronger than would be expected from its thc content alone. We dont know much about those other cannabinoids. Also often underplayed is the role of terpenes (chemicals that occur in other plants). Linalool for example is the principle relaxant in lavender. There are many others in pot, in various concentrations. The particular scent is the give away re:terpene content.