Relating to culture, saying a teaspoon (or a little less) isn't the end of the world, but culture strength varies from culture house to culture house, and even varies from lot to lot within each house. For instance, the culture I use comes in foil bags to culture 1250 liters of milk. The bags from different lot numbers vary in weight by as much as 3 grams. So, I calculate by weight as opposed to amount for much more accuracy and consistent results.
It sounds like your curds either hadn't firmed up enough, so stuck together quickly, or maybe the curd wasn't as well set before the initial cutting. Research flocculation on the forum to help you better to determine when to cut. As to stirring, I personally stir constantly. It helps prevent curd matting, as well as makes sure all the curds are heating at the same rate. More importantly, constant stirring prevents me from getting distracted and coming back ten minutes later when I thought only 5 had passed.
The pressing regimen as Smolt1 addressed, is pretty important to follow for established cheese types. Also, how long did you press for?
Mold is a struggle for nearly all cheesemakers. Why isn't it a struggle for all of them? Because, some of us believe in a natural rind. I am mostly a gouda maker, but the same would be true for me if I was mostly a cheddar maker: I don't fuss over any mold that makes its home on my cheese. Mold adds flavor. I rarely have cheese succumb to mold (maybe 1 out of a thousand). The most I do is dry brush each wheel before sale, or for one of my flavors, I oil it just before sale to make the color of the rind pop out.
If you're looking for a bit of rind protection, Web master John adds just a tiny amount of GC to his makes to help keep other molds off. I haven't asked him personally how well it works, I just know that's what he does.
I hope I helped, but take it all with a grain of salt.