Q1 to 3: Don't look at me :-).
Q4: I'd recommend getting an integrated ADSL modem/router/switch. Something like
this.
This particular device is for analog adsl and sells for about 130EUR in the Netherlands. Mind you I don't have this thing nor any experience with it. Just seems like a great solution to me....having all devices in one box.
My father recently got analog ADSL he was supplied with a
Thomson/Alcatel Speedtouch 510 (V4) modem/router. I simply hooked an 8 port switch onto the ethernetport of the modem, plugged 3 computers in the switch and hey presto. A beatifully functioning ADSL LAN.