The current file limits are 200 minutes and 200MB.
Resizing your clips
The limits should generally cope with pretty much any kind of content. However, some file formats (WAV in particular) tend to use more file space than they need for the same quality.
Resaving your clips as MP3 from WAV will give far better compression. (As a very rough rule of thumb: a WAV saved at 48k bit rate can takes up around 6MB per minute - the same 48k file as MP3 averages out at just 0.4MB per minute.)
Audacity is a free, open source desktop editing software for Windows and Mac that can convert many file types.