Is it possible to install Win7 from USB ?

I do not believe this is possible on the MacBook Pro's. When I downloaded the ISO from the MS website I burned the image onto a DVD. As far as I know, that's the only way to do it on the Pro. There might be a few workarounds but honestly I don't think they are worth the effort.

 

Agreed. This never used to be the case, but it's a fight to get a MBP to see a Windows USB stick with this generation. It will take much less time to just surrender an use a DVD.

 

Can't just copy the ISO to a USB key or extract it to it and have it bootable.

This is the easiest way, but need a Windows machine for the utility. Not really jumping through hoops..:

http://arstechnica.com/business/news/2009/12/-the-usb-flash-drive.ars

Once you do it, just put the key in a safe place...

Can be done with diskpart and a command line, but this tool simplifies things.

 

No, there's no problem running 64-bit Windows on these machines. Just installing is more of a pain than it needs to be.

 

The MBP EFI does not allow you to complete bootcamp without a disk. MBA and Mac mini bootcamp allow you to create and use Windows 7 USB install. You can do some EFI trickery to get the USB bootable. Getting through bootcamp is more difficult.

I have a question about getting bootcamp to work when the OSX drive is external. Basically, I want to legitimately create a bootcamp partition on 100% of an internal SSD while booting from an external Thunderbolt SSD. Basically, the goal is to swap OSX and Windows after bootcamp install is complete to get an external Windows Thunderbolt SSD.

 

I've done it from a USB Stick from within Fusion on my MBP, where Fusion saw it as a bootable disc. I'll give it a try today, I always carry it with me. I personally don't do bootcamp as my machines all have SSD's and I'm a bit averse to allocating space I may not ever use. by running VM's I use what I use and the rest is fee to OSX . I have booted from the same disc on my Mini though, which are more temperamental than a MBP to USB boot and it was successful.

You scoffed at the Idea of extracting the ISO out withot the secondary work, I commend you as any folks think that's all that's involved.

 

you can install windows without the dvd using parallels. You have to format that partition to ntfs, using the installation of windows. then copy everything from the windows usb onto the bootcamp partition using the command prompt from the windows installation(with a command I cant remember right now[xcopy something]). then reboot while pressing the alt key and select windows and it will run setup from there and install on the same partition without formating.

I've done it cause I don't have the superdrive installed.(optibayed)

 

Your answer although correct for any Virtual Machine Program is totally incorrect for using the Boot Camp system.
Which is what the OP asked.