Will i have problems using the 2 formats (ntsc and pal) in the one movie?
You betcha
Is it just a matter of fixing the setting in easy setup?
No. Although FCP can handle mixed frame rates and resolutions in the timeline its absolutely rubbish at doing so ... especially putting NTSC in a PAL timeline. It looks horrible and just drops frames all over the place. Bad.
Please.. any advice would be much appreciated.
Ok ... is there any chance you could ditch the NTSC cam and replace with a PAL cam? If so, do it now before you shoot any more NTSC footage you don't need. Even if you can't reshoot the already NTSC shot scenes (which would be great if you could) it would be better to stop using it now than just continuing down this particular 2 format path.
For the NTSC footage that you have already shot and/or will continue to shoot. The best conversion will come from a facility that can offer a high end hardware based standards conversion ... failing that you can do a darn good conversion yourself using Compressor's Advanced Format Conversions and utilising the Frame Controls, but it take a looong time. Graeme Nattress's Standard Conversion filters are also highly regarded.
Just some thoughts to be going on with