Once we have a separate forum area for this game, if we have enough interest, I will make sure it gets moved there. =)
Here is what I have learned about the great art of familiar gathering thus far.
Taming
Most animals can be tamed without special items. You will know if you have the ability to tame a beast if it has a symbol above it's head that is gold color. If it is gray, you are missing a required special item. A lot of named beasts have special items you acquire or craft in order to obtain them. You will learn how to tame via a quest in the game.
You can have more than one of the same thing in your set of familiars. For instance you want to keep one as a mount, but you want to seal some for the stats they put on armor or the talent point pool. (Seal Stones below on how that works)
I will note that you must have an empty slot to put a familiar in or you will be told no slots available when you try to activate the taming skill.
Mount vs Pet
When you first tame any beast it is automatically made into a mount for you to use. There are scrolls that rarely drop off beasts that allow you to change the mount into a pet. Unfortunately, so far the only ones I've seen came out of quests that require you to make a pet. The fun part of a pet is it fights along with you.
NOTE: I have not got a common pet scroll on a drop, but once in the 20+ area, I got some elite pet scrolls.
Seal Stones
These are used to capture the spirit of the animal into a stone. You can use them to enhance your armor. At level 20 you will learn how to use these same items to add to your talent pool for more skills.
Here's the crux of this currently due to initial level cap - you can easily buy common ones, but elite ones are very rare drops to the point that there are already comments about the area where you can get them now hardly dropping any. For the most part elite ones are supposed to drop off bosses in elite and heroic dungeons and some bosses out in the world. Too bad they are so hard to find. I have a couple of elites I would love to seal.
UPDATE: 7/4 - I got one elite seal stone and one elite pet scroll while fighting out in the 20+ area, so don't fret, they DO EXIST! And can come about randomly and off named mobs outside of the dungeons. Know I did kill at least one named mob out here so far.
Stats
Every familiar has a set of stats it has for mount/pet or for a seal stone. The stats increase as the familiar is leveled, especially noticeable and worth it for the seal stones to place on your gear. Some examples are: (NOTE: percentages for mount/pet do have a chance to increase, but slowly and some gain further skills when they level. These listed are mostly common familiars (one white star))
Woodland Joey - Mount/Pet gives 4% to max Energy Pool (EP) and Increased Movement Speed 15%. As a seal stone enhancement it gives Evasion Power.
Panther Prowler - Mount/Pet gives 12% health. As seal stone an increase to Physical Crit Damage based on level.
Cold Tusk (Elite) - Mount/Pet gives Physical Defense 8%, a skill to increase health 20% for 20 seconds, and an attack skill of Tusk Charge based on L16 stats. If you get an elite seal stone he can be used to increase your Health and Constitution.
Ambermane Caribou - Mount/Pet gives Magic Defense of 9%. As a seal stone it increases mana.
The one stat that does not change per level is the amount of Talent Points it will give if used to fill the talent pool.
Biggest Concerns
The number of familiars you are allowed is definitely restricted, but can be expanded with elluns. You will have to pick and chose what you truly want to do with each. There is one further option not mentioned to help with space. You can release them back to the wild if you decide you rather have the space than keep them.
The other concern as already mentioned for seal stones, is the rarity of elite seal stones versus elite pets you can get.
Conclusion
There is a lot to do with pets and based on your class you will want to make sure you pick the right things to have to help you out for mounts, pets and seal stone enhancements.
Enjoy the taming and see where it can lead in enhancing your character.