Requiring the billing and shipping addresses be the same is acceptable, though I would be sure to make that requirement very clear to your customers. Unfortunately, you might lose some business because of it. But I don't think it would be a huge negative.
Verifying the location of the IP address that the order is placed through seems like a big hassle that won't really save you much. If you can check the IP pretty much automatically I guess that's fine, but I wouldn't go through the trouble of manually checking it for each order. Maybe just ones you're suspicious about. And I suspect that a mismatch between IP location and shipping address is much more likely to cause you to deny legit orders than it is to save you from scams. Especially if you're shipping to the billing address anyway.
If you have big ticket items that people order with more thought, then 2-3 days of delay in shipping is probably fine. But if the cost is relatively low and it's an impulse purchase ethen the delay would be pretty irritating I think. Once again, if its going to the billing address I think the risk is pretty low.
Refusing orders from free email accounts is going to kill your business. The vast majority of legit customers are going to be using gmail, hotmail, yahoo, etc. Honestly I think that's a waste of time. The only emails I'd be suspicious of are those with wierd names that look like a random string of letters and numbers.
I know being scammed can be terrible (I've been scammed out of over $20,000 worth of products) and you should take precautions, but I think doing all of these things will be more trouble than it's worth. In most cases shipping to the billing address and having some sort of tracking (or requiring signature) should be more than enough protection.
Just my two cents. You know your business best of course.
