By including a deadline, you create a sense of urgency in the mind of the customer. If I don't order within 24 hours, then I won't get the bonuses. Oh no, there are only 10 items remaining, I've got to hurry. Let the customer know what they will be missing out on if they don't make the deadline. Remember, they won't miss out on your products or bonuses, they will miss out on all of the benefits of your products.
Deadlines are very effective.
Every sales letter should have one. Be clear as to the order process. Point them towards the order link. Tell them what methods you offer. Make this process as simple and clear as can be.