Thank you both for your responses.
Dave, thanks for the advice on frame rates. So best to change comp settings to 25p? Also, will this overcome potential problems due to discrepancy in frame rates of the different footage? (In other words, when i have a 25p comp, can I import different footage differing in frame rate without a problem?)
I am still in a process in fully understanding the differences between these kind of settings, as you can see 🙂