A:AnswerYou would have to set up installation with your local Geek Squad. Office 365 does come with easy to install instructions as well if you want to do it yourself.
A:AnswerI would go with a better computer. There is a 14 inch Hp using i3 processor, one thing of storage and 8 gig of ram and it maybe cost only $50 more (check for sales) and is much better.
A:AnswerThis computer would work excellently for light productivity and streaming videos. It does not have the spec for heavier multitasking but I see no issue why it would not work for the uses you mentioned.