You'll find a few sizes but let me comment about large screen laptops. Many folk get one and if they set it on a desk top and it is not carried around a lot they seem very happy with that decision.

Folk that get a 17 inch laptop find it's not that mobile and a little much to bring with you. If I need a big screen I plug in another monitor as you can see my old setup at
http://i175.photobucket.com/albums/w146/rproffitt2000/desktop2.jpg

Nod to the 15 inch models.

-> About software. There's a lot out there but be aware that your Office choices are not limited the Microsoft. Look up LibreOffice for Apple and the price is right.
Bob