Yeah, that's a good way to start. Don't really need to worry about the initial value as you can top them up once they arrive. You might also want to just order one online with your name embedded and pick up the rest at a Transitlink office straight away.

Withdrawing funds is not possible I think, or at least not something that can be done quickly and easily. You can move funds between cards though (in whole numbers - no cents allowed), or you can clear out a card (if you lose it for instance) by just making a Starhub payment for instance for the full balance of the card.