I would advise that you do get all the drivers for your laptop brand name and model number.
Windows 7 has pretty good driver support, but there are occasions where your Lan port of the laptop and that driver for it is missed by windows 7, and or the one for your built in wi-fi adapter also.
Meaning if it does it`s a nightmare because obviously you cannot get on the internet to download the drivers needed.
So yes get all of the drivers for your laptop if you never got a driver support cd or dvd with the laptop.
And burn them to another cd or blank Dvd disk also, to make life simple.
O r stick the drivers on a usb pen if you have one.
First answer to your questions Yes. Not oem, but a retail version, oem comes with the computer or laptop you bought pre installed.
Second the file you download will be an Iso image of windows 7.
You will need software to open the Iso disk image to burn it to a blank DvD.
You can use a trial version of power iso here to burn the iso image to a dvd.
Or got to Microsoft to get a tool to burn the Iso image to a dvd also.