Shamim's Plugins

2 options are available now. You can add one by one and/or all members of a role. You can also remove some members from the role.
Eg. you have added subscriber role, after save all members of the subscriber role will be added. Then you can remove some members from there also.

Answer-1: Currently there is no direct class to hide. You can override header.php template to hide that line. Follow https://www.shamimsplugins.com/docs/front-end-pm/customization/change-templates-2/ to change template.
or wait for next version. I will add a class there so that you can easily hide that line with css.

Answer-2:
It will automatically redirect you to message page where you can read that message. Redirect to any other page add following code in your theme’s (child theme’s if any) functions.php (Change YOUR CURRENT MESSAGE PAGE URL and YOUR DESIRE PAGE URL accordingly)

add_filter( 'fep_header_notification', function( $show ){
    $show = str_replace( 'YOUR CURRENT MESSAGE PAGE URL', 'YOUR DESIRE PAGE URL', $show);
    return $show;
});

You can download from https://www.shamimsplugins.com/checkout/purchase-history/

You can use fep_before_form_fields to show before form fields or fep_after_form_fields to show after form fields.

in “Threaded” view, message recipient is only set in parent message. So it is not possible to reply that message without replying to all recipient.

Suppose user U1 sent a message M1 to user U2 and U3. So M1 recipient list is U1, U2 and U3. So if U2 reply that message as R1, no recipient list is attached to R1. it use M1 recipient list. So if you want to exclude any user from R1 that is not possible as R1 has no recipient list. It uses M1 recipient list.

I do not see any logic to achieve what you want.

In “Individual” view, recipient list also attached to reply messages. In that case you can manually change that.

So you have to set “Separate message” or “Individual” view to achieve what you want.

are you getting any error related to this plugin in your server log?
7.4 is latest version and no update is there for this version, so update is not an issue.
did you changed anything (any code or new plugin) after installed this plugin?
Can you please install again this plugin and see if problem exists or problem come after some fixed time?

In that case you have to set “Separate message”.