Small Magento Modifications

I am using Magento e-commerce site, latest v. 1.3.2.2. I am having a few small issues with the site set up and need a Magento expert (may require some PHP coding) to get things the way I want them. I'd prefer not to give you access to my server unless absolutely necessary, so you should be familiar with these issues and be able to test yourself. Here is what I need: I am only taking payments with Google Checkout, Paypal Standard, and Amazon Payments. I am only using "guest" checkout, no accounts will be available for the user. Google Checkout: -Already set up and working just fine -Problem #1: when checking out, does not add tax to shipping charges (only subtotal is taxed) -Problem #2: User is being notified during "pending" status instead of "complete" status. -I have a custom addon that also includes a serial# in the order notification e-mail...so its important that the order is "complete" before sending. Paypal Standard: -IPN not working -Two possibilities--login to paypal account or pay with credit card on paypal page -Can we bypass one-page checkout since address info should come from paypal account or if they type in credit card info? -If not, one-page checkout needs to be simplified since only one payment method -Tax/shipping should work properly (shipping has taxed ADDED if they are from a certain state) -Order notification will have to work as in Google Checkout case Amazon Payments: -Not set up yet (unsure if there will be problems), but this should also work just as the GC/Paypal cases (for example, tax on shipping charges, AND, notification after complete). -Needs instant notification working after user pays. No-tax addon: -Need to create coupon code that will make it so that no tax will be added to the order regardless of user info. Other minor fixes: -Need you to help me address any other "minor" magento problems to have integration with my site work properly. This should be very minimal, but might be something like disabling certain features.