1. Can the protocol be changed? What if changing the protocol solves the above 3 problems which are limiting bitcoin as a currency for regular transactions?
2. If you have a limited number of networks say 10,000 to process a transaction this should reduce transaction time? And/or how many miners does it usually take to process a transaction? Not every miner right?

1. It can but only when the change actually solves something instead of breaking everything.
2. That is not how bitcoin works. Nodes verify transactions and enforce the consensus rules and prevent invalid transactions from existing. Miners only compute hashes on a block header that their node creates and gives them. The number of nodes or miners won't change the time between blocks, more nodes has 0 effects and more miners will have a temporary effect before the difficulty adjustment is reached and everything is balanced again (2016 blocks in 2 weeks target).