MyKobalt

1- If the fan blowing through the radiator is exiting "in" the case, your ambient will be higher. Make sure the exhaust from your radiator is exiting your case through the back or top. This will keep your ambient neutral.
2-You can pull the water block off your cpu WITHOUT disconnecting the hoses. Just be careful not to kink them.
3-FLuidXP, PC Pure, Themaltake's coolant.
4- I have no personal experience with that, but my guess would be that your CPU will only cool down as much as the fluid flowing through it. All the heat from 4 sticks of RAM will go right over CPU. I wouldn't recommend it. Most RAM sticks have sufficient heatsinks that will stay well cooled if you have a RAM fan cooler or even good air flow through your case.