http://www.psypokes.com/rs/berrystats.php
In emerald you get them in the contest hall by making them with berries.
Mulch
You have to wait for it to grow.
The leichi berry raises the attack stat if held by a Pokemon (that what it says in heartgold but I am not sure if it's the same in emerald)
Feed them good pokeblocks from durin berries.
Pataya berries must be obtained from either Pokemon colosseum or Pokemon xd gale of darkness trade a Pokemon holding the berry to emerald then plant it to get more.
Lum berries are randomly given out by the berry masters wife.
No you can water them infinite times and nothing bad will happen.
The berry type that will make beauty go up are all dry berrys.
You can find berries in these loamy patches throughout the game. You can also plant them afterward and water them, after a while you can receive more from the one you planted.
You grow it like any other berry: You plant it, water it (if you want more than two berries to grow) and pick the berries.