Most of my answers on those numbered questions are the same as the others so I would start here.
What of the above is an exploit and what is a scam ? Where does an exploit start and a scam begin ?
I agree that there is this line between exploit and scamming and I guess it should not be exploiting but cheating. It is unfair for a scam to be compared with exploit since exploit can be ended with a good cause while scam is bad and it just ends there. A scam in gambling is usually on the part of the owner of the site like lying for that provably fair or maybe saying that there are supports 24/7 but they don't really care most of the time.
And what about fixed matches ? These matches do exist, every day there is match fixing, but most of the time we gladly don't know or aren't aware. If you (get to) know about a fixed match and bet on it, does that make you a scammer/cheater ?
You are a cheater. That is an exploit in your side, those players are the scammers since people think they are playing seriously but they are not. @Lakai already said it and these team or group are scamming those people usually for the sake of money.
Gambling is a (most of the time unfair) competition in the end. Should the "software factor" be completely called immoral and unethical behaviour, when you take advantage of it ? If there is a line for you, where is it ?
Well, that is cheating and that is just unethical behaviour since you take advantage of it but if not, then that is just good, you know. This depends though on how you found that exploit, right? If you did some hacking and dived to their system, then that is just immoral and unethical behavior but still could end up good, isn't it since we have a white hat and a black hat hackers. As @Upgrade00 said, the intent is both important on two sides since that usually will be the deciding factor of whether they will be taking advantage of it or not.