Let me say something very briefly about meditation of loving-kindness. Here I would say one important aspect of meditation of loving-kindness is that it helps us to experience joy.
In the Buddhist model of meditation, first we work with what are called the hindrances or the obstacles. We can see them as unpleasant emotions. Then the next stage is working with them using loving-kindness or even using focusing on breathing. Then we can sometimes experience jhanas or the absorptions when these hindrances or unpleasant emotions are absent. So these absorptions or jhanas can be seen as positive emotions. And the next stage of meditation is that when there is joy, to remember not to identify with the joy but see that also as changing, as impermanent, and realise that we don’t really own this positive state of mind. So this in simple terms is one way of understanding the Buddhist model of meditation.