Question about Munchkin Polo Shirt

[codog27]

We need an official munchkin forum opinion!!!!

I have the Munchkin Polo Shirt, and would like to use it as a steed towards the beginning of the game. However we have a few questions:

1) If I would like to use another steed at some point in the game, can I simply take off the Munchkin Polo Shirt to equip the new steed?
2) What happens if I take it off, is the steed immediately dead/discarded?
3) Am I allowed to take it off at any time?
4) At what point must I declare the shirt as a steed?
4a) At the beginning of the game or at any point during my turn (outside of combat)?

Thanks in advanced for your help!!!!!!!!!!!