Mobile friendliness does impact the search rankings but specifically on mobile platforms. You can see a quite apparent difference in rankings in desktop search and mobile search for same keywords. So, if you rank high in desktop searches doesn't guarantee high rankings in mobile searches as well if you don't have a mobile friendly website.
As far as HTTPS is concerned so it has nothing to do with your search rankings, it is just make your website secure. So, if you accept online payments, you should go with SSL to keep your website secure and safe. However, as Tom Roberts mentioned, you might see some drops in rankings while you migrate your website to SSL due to migration technicalities
