Hi
1. For you were not able to upload LOGO issue, after you uploaded your LOGO, have you clicked insert to post button?
2. You can change the LOGO width and height in “Samsara options > General setting” without change layout.css
3. The easy way to fix your last issue is disable the Navigation Shrink Effect in “Samsara options > General setting > Disable Navigation Shrink Effect”, then the height of top bar will always be 135px
Thanks