Img size / Velocity / google fonts

Hello

1) I wanted to know how I can use google fonts in other paragraphs.
I use “Quicksand” across the page.
The only way I’ve found is shitting source from the drop-down css because of paragraph (enfold menu) lets not select “Quicksand” (on the menu of heading yes you can). Is there any way to do this without adding CSS?

The CSS is making slow my page, so I want to use the minimum code.

2) On the other hand. I would like to know the correct size (in pixels) must have images using the demo “enfold GYM”:

width and height of images Slide.
Width featured images
Blog Column Width … etc.

What size deverian have on this template (gym) to be optimized?
I searched the documentation, but I have not found anything.

3) I used “enfold GYM” to build my website. but without applying any changes, nor any plugin installed … the page speed is very slow. An average of 5 seconds to load! Is a long time, I think enfold does not behave well with speed. Is there any solution from the template itself?

I think “php7” could help. Enfold supports php7 correctly?

4) Is there any way to make a button there will be a media file with lightbox? I mean a botton (not an image) can open a medium (eg a youtube video) in a lightbox. Without having to go to the link of the file on youtube or on my server.

Regards, and thank you very much