1) Dual booting any operating systems is a risky operation. To minimize the risk use a third party boot manager to set up and install the operating systems. This allows the Master Boot records to be controlled and hidden from each separate OS other than having them over-written by the windows boot manager to a single master boot sector.

I use BootIt NG from terabyte International as my boot manager. It is not free. A free one that is becoming very popular is GAG.

2) BootItNG and GAG both have built in partitioning capabilities and are recommended to use for more than the 4 partitions that microsoft restricts to, There are plenty of other applications such as partition magic. Google would be your best bet as each one is different and requires a higher technical background as the next one.