You showed us before an example of your website that we have been checking.
About your problems:
1, 3 & 4. Please, contact your hosting provider to ask them if they have any protection over POST and GET forms submissions that are adding additional backslashes to escape “the original” ones. They should understand this problem and provide a solution.
2. This problem may be related to the previous issue too, or it can be a basepath issue. Check this thread to learn how to use the basepath setting https://responsive-muse.com/forums/topic/easyblog-v2-update-new-features-and-bug-fixes/
It makes no difference if you are using free or pro version, first you have to fix this issues with your server before using the widget.
I hope it helps!