THREE RHYMING RIDDLES

1)
An indication of pleasure,
An equine measure;
A help in time of need,
Don't bite the one that feeds.

2)
This thing you must keep,
And not lose on your brothers;
For once yours is lost,
It will soon be lost by others.

3)
Through my first forever flow,
Sounds of laughter, sounds of woe;
In my second do thousands rest,
Though not one is a human guest.
In my whole there is no jest,
Promises are made, regrets confessed.

Answers:

1. HAND 
2. Your temper
3. EARNEST (EAR / NEST)