menu bar – different devices

Hi everyone!

I am using the organization theme and the website I am talking about is residua.co

I am having a few issue with the navigation (menu bar) on my page. I cant remember having changed anything, but suddenly the bar is much further to the left and not in the middle anymore. The same with the header! It looks fine on the mobile version, but not on the pc version. Can anyone help me with this?

Also, I would like to add the social media icons on the right side corner, just above the picture, on the same height as the logo. I tried adding it to the header, but it either displayed above the logo, giving far to much space to the top part of the page!
Can anyone help me with this?

Another question (sorry for all the questions) is, on the initial page I have 3 columns, I would like the button to read more to be on the same height (i thought I can change that with changing the variable from max length of words, to max length of letters, but it only changed for two) Can anyone help me with this too?

Oh one last thing: I uploaded a picture as feature picture (see http://www.residua.co/que-es-residua/equipo/) and it cuts off at the side. We already adjusted the size of the picture, but that wouldnt change a thing. Any ideas? many thanks!

Many many thanks in advanced!