1. No, you'd have to take the cocoa above about 160F before you reach any issue (correct me if I'm wrong?)
2. Lots of variables here. Could be not enough CB as said above, could be over refining (this is the issue I run into the most), could be too much moisture in the mass. I usually refine in 2 stages, the cocoa beans for about 4-6 hours until they go smooth, then add the sugar and go for another 12 hours.
3. Think of these temperatures as a working guide, maybe you just need to work at a slightly higher temperature, have you tried? I actually work a degree below most guides usually, depending on the chocolate in question.
4. Hard tapping is fairly normal I think. Difficult if you only have the flimsy moulds but no problem with professional ones. I give mine a good hard bang about 4/5 times before putting them in the cooling fridge. The finished surface results will be directly related to the quality of your moulds too.
5. Stir gently, but don't stop, both are right( I never temper by hand though, those days are gladly behind me!)
6. See #3
7. It's more efficient to cool a smaller mass of chocolate compared to a larger mass, which you only have to reduce to your working temperature.
Hope these help, it's just my own meandering experience.
Everyone should just do whatever works best for them Joe if I had a tempering machine with active cooling (way out of my budget), or if I could actually manage to keep my factory around 16-18C (need a new air con unit!), then I wouldn't need to use silk, but I find it helps no end by cutting out that extra time dropping the chocolate 4 more degrees, saves about 3 hours a day at least in the warmer months.
I just have a few hundred grams of liquid silk sitting in a bain marie 24/7, nice and easy and takes off at least an hour from my tempering cycle with my Rev V. I haven't got round to trying to make solid bars of it yet, I tried once in my Rev but it didn't work.
I've not worked with less than 3kg of chocolate, measuring a small amount like that might be tricky on kitchen scales, you might be able to get a small cheap one on ebay that does small measurements like 0.1g for being exact.
Hmm, it's hard to say then. Presuming the cocoa paste you have is nothing more than smooth 100% cocoa liquor, it should have turned into a gritty paste (think of it a bit like concrete imo), but still a workable paste you can put into moulds. Obviously adding cold sugar will reduce the temperature of the liquor, so you could end up making it tough to work with if the temperature dropped too low, but I presume you are familiar with all that as you've already been tempering chocolate.