How do I set things up so I only have to edit a layout once (and two other newbie questions)

I feel really dumb, heh. I checked the FAQ and couldn't find anything that explicitly told me how to do this, and I am extremely ignorant about web design in general.

How do I set a site up so that if I want to change anything on the sidebar I only have to change it in one file and then it is updated on every individual page? I thought it would be somewhere in the stylesheet but I just can't figure it out.

Also, when I was checking through the FAQ I saw the thread about not using tables. My site is really just a bunch of Excel-like data. Is that an acceptable use of tables? It seemed like the only real problem is using tables for forced spacing... which I am also guilty of doing but don't mind cleaning up.

And finally, what is standard page width these days? Since I don't know what I'm doing I don't need it to be mobile friendly so I've had it set at 1280. I found a thread that said 960 should be the max, though?

Thanks in advance.

Epic visual tool

Epson 5030UB 2D/3D 1080p 3LCD Projector Submitted October 27, 2015 at 02:16PM by AngryBeev http://ift.tt/1MpsvSJ