Help required for inputting icons

Hello people, I’m wondering if anyone can help me please. I have created my Squarespace website (still a few things I need to add/do). However, I’m stuck with a few things that are really bugging me. I have seen posts on this forum before asking for similar / the same things but for me they haven’t worked.

I need to install the Whatsapp icon for my header and footer – I have attached a PNG of the logo to the coding / css section (which I’m clueless with). But I can’t get it to go on the page.

I also want to install a search icon (not search bar) – preferably to a drop down search box, identical to the one Squarespace have themselves when using the settings section. Aswell as replace the ‘login’ with a little login person icon. 

Finally I want to add a ‘sorting’ drop down menu / box on my product category pages. With ‘sort by popularity, alphabetically, price low to high’ etc.

I’ve got these ideas from a competitor site, which i've attached a picture of, which shows the icons on the header, and also shows the sorting options on one of the product pages. I have also attached the mobile version and how it is laid out. 

If anyone can help me, I could give the login etc. I’d greatly appreciate it. I’m happy to pay someone to help if these things can be done.

(I’m also wondering is it possible for me to add the ‘pay with apple pay’ option on my product pages – I was told it isn’t?)

Thanks

Josh