To save time, unpin every tile from the tile screen and then pin back the ones you want and use, that way from day one the phone is yours and not covered with tiles you don't want.
Go into settings and change colours to a scheme you like, I went for Xbox Green, my lad has his set to sh*tty brown and my wife has steel on her phone all with the dark background.
As mentioned you need a Microsoft account with an Hotmail or Outlook email address but that doesn't stop you adding Gmail (I still have an email account with them) although I haven't used Exchange I am sure it will set up OK.
You get OneDrive with the phone, probably 15 g, you don't mention if you have other PC's etc, I haven't used Dropbox, but can recommend OneDrive especially if you are an Office user with Office 365 as currently you get 1TB of storage and this is going to be Unlimited (A lot).
And sorry I do have to say this, get yourself an Xbox One, take a picture on the phone, it uploads to OneDrive and is then viewable on your telly without any real work on your part. In other words the integration between MS stuff is getting really good and that is before we get Windows 10 :smile:
Enjoy your 1520, I know I enjoy mine.