OsCommerce Tasks - UPS / USPS tracking, Account Types, Discounts

We have a osCommerce 2.3.1 website set up and need several enhancements added to the site.

1) Quantity Discounts - Example: an envelope costs $4, but if you buy a box of envelopes (qty: 10), it will cost only $20. But if you 11, it will cost you $24 ($20/box, $4/envelope)

2) Account Types - We'd like to have different account types, so different customers have different prices for products

3) Shipping Tracking - We'd like customers to be able to type in their tracking number and have their tracking information (UPS/USPS) listed.