Concerns about reading a file in Flash 10

I'd like to read an xml file on a user's machine (which can be kind of large). There's no point in me sending the file to my server as I can do all the work I need on the file开发者_运维知识库 right on the client's machine. Not sure if this is a good fit though, was wondering if anyone can answer these questions before I dive in:

1. I see at adobe's website that Flash 10 has like 94% penetration, is this true, I thought it was just released not too long ago?
2. After opening the xml file in flash, is it possible to just throw it to a javascript function on my same page for further processing? I'd like to go into flash world for as short a time as possible.
3. Is it at all common to use flash for file upload stuff? I heard aol/flickr are?
4. I would need to buy flash in order to do this right, they don't have a free ide/compiler yet?

Thanks

1. I would trust Adobe's numbers as far as penetration goes. Since they've implemented express installation/upgrading, it's been very easy for most people to update their flash player. If you want to require Flash 10, and have it automatically prompt the user to upgrade, look into something like SWFObject (all the user has to do is click the "okay, upgrade" button. Flash will then automatically download and install the update).
2. Yes. You want to look at the ExternalInterface class in AS3.
3. Yes. Gmail also uses Flash for this purpose. The only other reasonable alternative is Java (or the HTML File API once that gets support in most browsers, but that's a little ways away).
4. The Flex compiler is free. I have no experience with Flex, but you could certainly do this in Flex. The Flash IDE is what I use, but costs money.