1. yes its. but if they find video on page, it will automatically stop. so it maybe you have video on your blog.
2. i see some error on the code. it may cause by other plugin. can you try to disable all plugin first and see if its work?
3. you will need to use PNG file with transparent background. i see your logo is pretty good. but it having white background that make it look weird.
4. no its quite fast on my side.