No, the primary reason is that a mandolin has wire/steel strings, an ukulele uses gut or nylon. The tension required for a steel string is not going to be good for the instrument. Other reasons: They...
The related question below talks about the various tunings and strings for an ukulele. The mechanical process is pretty straightforward for those that can be done with a simple knot at the bridge...
No, though some can be used for both depending on the size and type. Metal strings are seldom used on an ukulele as the instrument is not designed for the stress.