FCP plays whatever I put in it. Why don't you just try it out and drop an audio file in at the settings you wonder about? That's the best way to find out.
The question wasn't clear sorry, English isn't my first language.
I indeed tried that and everything seems fine but I was wondering if that's advisable in a technical/engineering (ish) point of view. Having two different bit rates and frequencies in the same sequence. And if the render is the way to go or it's best to convert everything to the same frequency/bit rate.
By the way Chadfish, thanks for your video on the Lapel mics. It cleared some doubts, I decided to go for the Rode lavalier...
Fernando, as I have found - if it works, it works. I often use both 44.1 and 48k audio in the same timeline because my video is 48k, but the music I use is 44.1k. There is no problem, and no degradation of the audio. It's totally fine. If it does not work you will know it because you won't hear something.