OK Loko I'll bite, again, you can play me almost as well as my younger son - my answers to your questions, which are intended to be informative despite the hint of sarcasm, are as follows
1. No one thought of doing it in the professional game - clubs had been playing one day cricket for centuries, but overs limited cricket wasn't unknown
2. You can have as many subs as you like as long, generally, as they don't bowl or bat
3. The clue is in the name of the game - cricket as opposed to baseball or rounders
4. In days of yore there were often two, in the sense that the wicketkeeper always stood up and there was a long stop as well - I know that's not what you meant, but the point you meant is just plain silly