dual boot -WINNT and RedHat

Starting with question 1.
You can start cfdisk or fdisk under redhat (This is from a command shell, I don't know exactly how to do this from Gnome/KDE etc.)
Try fdisk /dev/hda (When connecting the harddisk to the first ide port, for other options check the man page of fdisk).
If you do not have enough harddisk space, you can add another harddisk, or repartition your disks. When you repartition your harddisk, install NT first, then RedHat. NT overwrites your MBR. When choosing to add another HD, make sure you have a bootdisk for Redhat when installing NT.

Q2. For making your system dualboot you can use two methods: 1. Lilo. type liloconfig to create a LiLo configuration file (follow manpage, or check http://howto.tucows.com)
2. Install RedHat, "capture" the bootsector, and write it to a file. Then edit your boot.ini on the Windows NT partition. Add a Line with Redhat and add the bootsector as file to this line. Also for this, check http://howto.tucows.com

Hope this helps.

Waitaminute!
how many hard drives do you have? If you have only one you cannot do it. There can only be one primary partition per drive. Having two operating systems on one drive is courting serious trouble. also the partition that linux boots fromhas to be set active and though they say that linux can boot from a logical partition it's not possible to have two active boot partitions on one drive and the linux boot partition must be active.
There is so much information I have to share with you that it cannot be covered here in this limited space. I will send a personal email and give you the details.