If the refurbished laptop you're being offered is less then 4GB RAM, then the rest of the specs might also be inferior to what you already have. If your friend is looking to get you a xmas present, perhaps you can suggest camera accessories instead. Or a replacement battery on your current laptop, if that's the main issue you're having. Here's a video on removing batteries from different Toshiba models:
Toshiba Tecra Battery Removal
To specifically answer your questions about swapping parts, it may not be as easy as just physically swapping parts. For the hard drive, is your Toshiba's HD as fast as the refurbished laptop you're thinking of swapping in? If you do swap, then you run the problem of Windows not being able to boot, since it's looking for all the components from the Toshiba laptop. So from a practicality standpoint, it would be best to back up your data on an external drive, install the Toshiba drive into the refurbished laptop, do a fresh Windows install on your new laptop, setup all programs, and then load in all your saved data.
With RAM, you have to check to see that you have an available slot, and if you have an extra RAM chip from your Toshiba. There's also an issue that RAM speeds will be different, so the computer will drop down memory speed to whatever RAM is slowest. Many laptops now have their first RAM slot practically inaccessible, so user accessible RAM tends to be the second slot that's at the bottom panel of the laptop. Your current laptop either has 4GB per each slot or 8GB that may not be accessible (at least not easily).