Frame rate

Hi, I'm an audio technician and lately i started to make some simple videos for musicians, so I encounter some difficulties dued to lacks of knowledge.
In my last videos i noticed that recording at 25 fps I had problems syncing audio, because we use more points for a second of time and not only 25, so I decided to increase fps to 50 while recording. I used 5 camcorders, 3 of them at 50fps and 2 at 25fps and I created a timeline at 50fps.
I thought that at the end of the project I could have downgrade the export file at 25 fps, but my only choice is 50.
I imagine that my audio way of thinking is wrong for video, so I have two questions:
1) Can I export at 25?
2) Which is the best way to manage this kind of job next time?
In my last videos i noticed that recording at 25 fps I had problems syncing audio, because we use more points for a second of time and not only 25, so I decided to increase fps to 50 while recording. I used 5 camcorders, 3 of them at 50fps and 2 at 25fps and I created a timeline at 50fps.
I thought that at the end of the project I could have downgrade the export file at 25 fps, but my only choice is 50.
I imagine that my audio way of thinking is wrong for video, so I have two questions:
1) Can I export at 25?
2) Which is the best way to manage this kind of job next time?