Sorry to only answer one part ;)
- In Australia we use physical Phone Splitters for our internet physical connection. One side of the splitter connects to a phone line port on the wall. The other side has 2 ports, one for the phone line connection and one for the router/adsl connection. If I have 2 routers I'll need a splitter that has more than 2 ports so I can connect the 2nd router to the internet. Are there Phone Splitters with more than 2 ports and do ISP's allow me to do this?
AFAIK, all those 'splitters' do is run a high-pass filter over the 'phone' side of the connection so that you can't hear the high frequency modem noises on your phone. They're not required, except to shield any telephony devices.
They don't actually 'split' the line. To use 2 ADSL modems simultaneously, you'd need two physical copper phone lines leading into your property.
To use two routers, I'm guessing you'd just have one modem and 2 routers, or one modem/router and one router.