Bitcoin has a mechanism that specifically blocks moore's law, and algorithmic optimizations. As the computers on the network get faster (i.e. the total speed that bitcoins are being mined increases) then the problem that has to be solved to create a bitcoin becomes harder. Read more
Just practice, practice, practice. Download a book from http://www.gutenberg.org/, and type it.
Compatibility overhead should only affect throughput (e.g. downloading large), and not (significantly) affect ping times. So if you're mostly concerned with playing online games, or browsing media-light websites, mixed mode will be fine. Read more