Redmine

We are using Redmine for our project ( https://bugs.freenas.org ).
I need to send e-mail notifications to our developers, for bugs that are assigned to them
for which they have not updated in the past 7 days.

I took a look at RedmineReminderEmails , but the existing reminder.rake script is
not flexible enough for my needs. For reminder.rake, I need to know exactly
the numerical user id of each user for whom I want to send a notification e-mail.
This is not good enough. I need to make a list of users based on some database query,
and then send e-mail notifications to each user.

I took a look at:

1. Reminder code in Redmine:
   • http://svn.redmine.org/redmine/trunk/lib/tasks/reminder.rake
   • http://svn.redmine.org/redmine/trunk/app/models/mailer.rb
2. Redmine Update Reminder plugin by arkhitech:
   • https://github.com/arkhitech/redmine_update_reminder.git

The arkhitech plugin came close, but didn't do exactly what I needed.

Therefore, I wrote my own plugin:

https://github.com/rodrigc/redmine_plugins/tree/master/plugins/email_notification

This plugin does exactly what I need. This was my first time writing a Redmine plugin!

I would like to make this plugin more flexible.
Instead of hardcoding the ActiveRecord database query inside a rake task,
I would like to create a web page where I can use the query editor to construct the query,
then I would like to save the query in the database.
I would also like to be able to create and edit multiple queries from the same
page, and then save each query in the database.

For each query, I would like to save this information in the database:

1. The database query which selects all the issues
2. The time interval by which to execute the query (once a day, once a week, etc.)
3. In addition to the Assignee, I want to add any e-mails to CC: with the email notification

Is there a plugin which does all this?
If not, can someone suggest some coding examples for how to do this?
How can I re-use the query editor in Redmine in my own plugin?

Thanks.