yup..you're in for a lot of fun with that cycling process...i did the same when i first started out..it's not fun, until you figure out what is going on your buying all kinds of things for your tank and for your fish and not having a clue why they are always getting ill.
as far as the gourami, your research is right, one will have to go.
as far as the aggression, well you now know about the issues with two gourami together...but as far as the mollly, i have actually had similar experiences. if you type "gourami molly" in google you'll find a lot of other people have gone through similar experiences. once when my girlfriend was over she got all worked up because of it and made me separate the gourami and the molly. i did..then a little later put them back together, and they went right back at it.
so i'll tell you my gourami molly story.
first two (dalmation molly, dwarf gourami):
for several days the molly would pick on the gourami. peck the side of his body, his fins, even once on his mouth i saw (and i don't think it was a kiss haha). i had no idea what to do..so i tried to break them up whenever i could, i did put the molly in a separate tank and then re introduced it (that tank wasn't cycled and was too small for the molly to stay in), and it went right back after the gourami...i couldn't believe it cause the gourami never fought back on bit i didn't know what it's problem was, it looked like it could easily fight off the molly.
however after a few more days..i noticed the gourami staying in one area..whenever the molly came around, he would start to turn towards it, and then the molly would run away...i watched some more, and every time the molly came in the gourami's territory the gourami would start to chase him away.
in the end...they all got ich and died anyways haha...that was the result of my uncycled tank mistake..
my current combo (balloon molly, dwarf gourami):
i first got the balloon molly, then the dwarf gourami...and i couldn't believe my eyes! the little balloon molly would peck the gourami!!
they basically went through the same process though. after a week or so they get along fine (they just swam past each other with no issue as i typed this). the other night i saw them like beside each other a little apart "sleeping".
so i think they just have some issues at first, and get things worked out eventually...my gourami is still a bit of a bully sometimes, he'll randomly dart at some of my fish..but he never seems to catch them.
oh i also have a 10 gallon by the way..
now some cycling advice.
read those articles so you understand what is going on, and what you must do. some of my personal advice, you can take it or leave it really, but i think you should get:
melafix
an airstone and airpump
aquarium salt,
quICK cure,
stock up on dechlorinator products (just get a big bottle, or get a bottle for ponds, you'll be doing lots of water changes)
an API MASTER TEST KIT (or something similar, you'll want to test for ammonia, nitrite, nitrate, ph{not entirely necessary yet but good to know it's at a safe range})
Ammo-lock (double check that this is the correct product)
melafix - i think it's an antibiotic, i feel occasional doses can help keep fish healthy, help slightly damaged fins grow, i dunno w/e..i'm no expert just my feeling
airstone/pump - you'll read that ammonia reduces O2 in the water or something..and i think people say that adding an airstone helps the fish get more o2 and also can help release things from the water since it moves the water around more and aggitates the surface
aquarium salt - the type used as medication (it should say that on the box), this can make the fish build up more of a slime coat so it will help protect them...i guess..it is also pretty helpful with ick, and although it's not like marine salt, i still think it will make your molly a little more comfortable (they actually like brackish water, but many people don't keep them in that, and it's not a terribly big deal, some people just notice better health in brackish water)
quICK cure - i believe i've read this is the best med. for ick..i've had it work..and not work..the trick is to catch the ick as soon as possible so if you've already got the product it will make it that much sooner that you can treat your fish instead of waiting till you get a chance to run to the store. ick is one of the most common issues beginners have (i've had a case of it almost everytime i've kept fish), also because many lfs don't take good care of their fish and they might come with it when you buy them.
dechlorinator - if you're really going to keep fish and your going to stick through this, you're going to be doing lots of water changes, each one requiring dechlorinator, save yourself a lot of cash and just buy a bottle marked for ponds, it's the same thing just more concentrated so you don't have to use as much.
test kit - you'll need this to tell where you are in your cycle. after the cycle you will need it to check occasionally that your water is staying safe and within the desired range. also if anything goes wrong with your fish or anything unusual with the tank testing can help you figure out what is going on.
ammo-lock - i believe this is the product that changes ammonia (bad for fish) to ammonium (tolerable by fish, still food for good bacteria in your filter, so your tank will still cycle). however there is another product "ammo lock" no dash, that neutralizes (or something) the ammonia, which stops your good bacteria filter from developing. saving your fish from ammonia will help their health alot, however nitrite will still come about, and this is also bad for the fish and you'll still need to change water a lot and stuff...but relieving your fish of ammonia stress will help their chances of survival a lot.
i know i wrote A LOT..i've just gone through...probably the exact same thing you are. so i know what you are in for and what to give you a heads up. as far as those products i suggested...it all gets very costly..but if you can just bite the bullet and get some of this stuff now, it'll help you in the long run. fish keeping is suprisingly expensive to start, but once you get it all up and going it's a joy.
i've been doing loottsss of reading but i am also a beginner. so if any more experienced people give different advice i would listen to them.
good luck!
p.s. i know i suggest picking up some odd products...but be very wary of anything that your lfs tells you, you NEED. sometimes they might be right...but sometimes it's something like..i dunno algae remover or something..you don't need a chemical...you need less direct sunlight, maybe lower temp, maybe different lights..it's very rarely a chemical issue. do your research.
that's far too quickly.
