Google PPC and Regional Demographics

Well, g'mornin everybody...(at least for those of you on New York time...)

I'm looking for some experience here that others have had using various PPC campaigns and the results they've gotten.

I fired up a brand new Google PPC campaign earlier this week. Its running 24 hours per day, in English of course, which does cover a lot of the world. However, I get a heavy amount of signups during the night - which means for me, that I have a lot of people signing up from Japan, southern parts of Asia, and Africa. I'm selling/providing business related materials.

My questions for the experienced Google PPC crowd,

1. do you limit your campaigns during a certain time period so that your entire daily budget isn't used in a certain segment of the world?

2. Do your conversion rates ($$) differ between North America, Europe, Australian, and Asia subscribers to your lists?

One of my concerns is that if I set a daily budget of $40, for example, I can chew through that $40 hours before dawn even breaks in the eastern US. As a result, Western Europe and the US don't see much of my campagins. But I didn't necessarily want to exclude a specific region either.

What successful strategies have you guys/gals used?

Talltom