Questions[seo]

I am generating the sitemap through PHP, since I want to control the URLs that are indexed, but I have a question, since before I did not use friendly URLs and now I do.

That is, for example I have this structure:

<url>
  <loc>http://www.miweb.com/contacto.php</loc>
  <priority>0.8</priority>
</url>

Should I change it to this one?

<url>
  <loc>http://www.miweb.com/contacto/</loc>
  <priority>0.8</priority>
</url>

That is, change contacto.phpto /contacto/. I had planned to pass everything so that it would appear with friendly URLs, which I understand will be better for Google robots to understand what is in the URL.

I have a client who wants his web page to appear in google with the following structure:

The client is already positioned, but it does not have the structure shown in the image. What must be done for the subpages of the page to appear, worth redundancy?

I am aware that nofollow links are specifically enforced so that search engine bots do not follow that link.

The reality is that this link attracts visitors and my theory is that a link, even if it has a nofollow for Google, for example, still has value, even if it is 1% compared to one without the nofollow.

Apart from this, what are the following values ​​for the rel attribute for because I don't see reliable information about it (the one that catches my attention is external).

I've only seen info here: http://www.w3schools.com/tags/att_a_rel.asp

But it doesn't explain if there are differences in SEO issues or browser behaviors.

I have created several links to https://japanpanda.com/ being nofollow (On other pages) and I have not seen any changes except improvements in referals.

It turns out that I need to hide some text but only on the mobile version, I would like it to be visible on the desktop version only. It is that in the desktop version the text can be placed thanks to the higher resolution, but in the mobile version I have to place it below and it takes up too much space.

I don't know if Googlebot (or other search engines) takes into account all these things, or only what is shown on the desktop version

Would it be detrimental to the SEO of the page? Thank you very much.