I had a similar problem with my laptop. The CD/DVD burner drive was making a lot of noise every time it spun up a CD. So what I did was take off the back casing of the notebook, and then remove the screws holding the drive in place. Then I re-seated the drive and put the case back on, making sure everything was firmly in place. Afterwards, it worked fine, without any excess noise. The problem was simply that it had become loose and was rattling against the case when it spun a disk.
If you have an external CD drive, then you have everything you need to install a new hard drive. The only problem is that you'll probably not be able to install the OS from an external drive onto the new hard drive; the computer can only communicate with the external drive via USB once you've installed the OS. However, you shouldn't need a floppy drive for any reason of which I'm aware. I don't have a floppy drive in this laptop, or any computer I've owned for the last few years, and I've never had a need for one.
50 minutes sounds slow for 4GB over a USB2.0 connection, but I've done worse. I've sometimes spent several hours backing up hard drives, before USB2.0 even came out. I've also spent several hours transferring files over a wireless network connection. 50 minutes is no biggie.