Okay, so, I'm in the market for an additional hard drive and I was thinking about getting an external USB one. This drive would mainly be used to hold music and movies, but eventually I might install programs/games on it. However, I have a few questions about them:

• What kind of speed am I looking at to transfer my current music/movies to this new drive? (mb/s?)
  
• Can all my future music/movie downloads be downloaded directly on this drive? ( Instead of my main drive then transferring )
  
• Can I play all my music/movies directly from the drive?
  
• Could I take this drive anywhere and play music/movies on others PCs?
  
• Could I take this drive anywhere and run programs/games on others PCs?
  
• Do these drives overheat or die more often then an internal drive?
  
• Are these drives louder then an internal drive?
  

Thats all I can think of at the moment. Also, if anyone wants to suggest a good ~1TB drive that would be great. Newegg links are fine. I'm willing to spend up to ~$250 dollars, but less would be nice.

1.) USB's transfer rate is 480mbits/s or 60mb/s. I don't think you can expect that much though, after doing some research it seemed like you can expect maybe 25~mb/s. I think it depends on the external harddrive though.
2.) If you configure it to save them onto the drive instead of your main one.)
3.)Yes.
4.)Yes.
5.)Yes, but there may be some problems, since you won't be bringing the registry files that programs install along with you on your drive.
6.)Depends on the normal enclosure. You should be fine, though, since both enclosures and external harddrives are designed with cooling in mind. Some enclosures run cooler than others.
7.)Depends on the actual harddrive inside, if there is any fans in it, what the enclosure is made out of. Also depends on what interal harddrive setup you're comparing it too.

Personally, I would get a 750GB HDD and put it in my own enclosure. 750GB HDD's are a lot more common, and have a much better price at this point. I do not think you'd find a good HDD + enclosure deal for under 250$

My recommendations:

HDD: http://www.newegg.com/Product/Product.aspx?Item=N82E16822152100

Enclosure : http://www.newegg.com/Product/Product.aspx?Item=N82E16817145126

_{Is the assembly tricky at all if I buy them separate? And how much am I looking at for a good HDD + Enclosure deal? And is it just simpler to buy just a normal internal hard drive?}

Assembly tricky? No, just requires screwing a few screws (if that) and plugging in some cables.

Just looking on NewEgg for something offering something similar, I came across this http://www.newegg.com/Product/Product.aspx?Item=N82E16822136176
It's a bit bulkier, I think. It is one of the cheaper 750gb external HDDs from a brand that I trust.

Simpler? Both are simple processes, I think. There's probably more work invloved in installing an internal HDD rather than an external HDD.