Um, the level of your neopet matters if you want to train it. At the Training School, you can only train a stat if it is less than double your level. So if you're level 10 with 22 endurance points. You won't be able to train in endurance until your pet is at least level 11. (11 x 2 = 22) Also, once you're level 50 or above, your pet can use berzerk in the battledome.
Your question is kind of hard to answer, it's more of an opinion type answer, some might say 100 is high, others might think 500 is. Either way there is no fixed answer. Here's a link that I found that should help you understand more about pet stats and the training needed for those stats, hope this helps: http://www.neopets.com/~gerkel