In our theme you can upload both SVG logos and the standard PNG logos. Whether you want to use a logo svg or png my advice it is to add an image without transparent or white space around the logo in order to set easily his position and size in the header.
If you need to add the logo you need to do it via customizer. Please follow these steps:
Note : If you wnat to add you logo retina remember that the new retina detects your image at a double-pixel density. For this reason you need to upload your logo at least twice the displayed size. For example, if your logo needs to be displayed at 100px width, upload your logo at least a 200px width.
For optimal WordPress usage for change the favicon the theme use the native WordPress function as presented in the official WordPress documentation here.
For add you custom favicon please: