you'll only be able to use whatever models you and the server you're connected to have in common. anything else you have will not be selectable, and anything else the server has will show up as default kyle.
i don't know the exact number of models that show up in the menu for you to choose from, but there is a possibility to have too many to 'officially' choose from. the problem with that is knowing what the model name is so you can choose it in the console.
however, in my humble opinion, you can never have too many models and/or skins ... it's an addiction.