Admins can’t edit each other’s posts

After I imported content from another wordpress site using the WXR export/import tools, my admins can’t edit each other’s posts. This is really aggravating because I can’t figure out how to change this. And it doesn’t just related to imported content. I can create two brand new admins, each one creates an entry, but neither one can edit the other’s posts.

How can I let users to access plugin functions based on roles?

I use a plugin called “Live Edit” to let authors and editors edit the content front-end. But the issue is that the plugin lets any logged in users to edit the content. I want the edit(specified by plugin. Not the WP’s default edit button) button be accessed based on their roles. I don’t know how to make it accessible based on roles. So trying to make it appear only for the authors and higher roles to that.

importing users where password is provided as md5 + much metadata

I have a spreadsheet that was provided to me of users to import to a new site I have built. I was provided with the password in MD5 hash form. I suspect if I insert this into the password field in the database, since it is MD5 it will still match their password when the user tries to login on the new system. Is this a correct assumption?

How to display the names of users from a specific group with a shortcode?

I have in the database a table with the user_id and corresponding group_id values, so each row contain the ID of the user that is a member of a group and the related group ID. The question is: How to display the names of users from a specific group, plus some metadata, with a shortcode, for example [group_members group_id=1]? With the bellow function, that I try to adapt for this without success, I can to display only the user ID or the group ID.

What is the best way to avoid spammers registering to my blog?

I would like to be able to easily control who registers to my blog because recently I had tons of spam users registering.
I came accross the plugin Stop Spammer Registrations, but i’m not sure it is reliable enough and I would also like to have a full log of every user who was rejected by the plugin/service.
Is there any good alternative?