Custom user field Available Credits

When a new user signs up I would like to create a custom field that stores users starting Credits.

I would like to display the Credit Amount for the customer on a product page so the customer can view their Available Credits.

I would also like to make it that the Available Credits field can only be edited by the administration of the website. The user should not be able to access this information in their member edit details page.

The idea is the users will receive a starting credit amount, This is viewable by the user so they know what purchases they can make from the website. After they purchase products or services from the website. An admin will manually adjust their Available Credits amount. The user should not be able to update this field as this would allow them to have unlimited credit to purchase more then the alltoted amount.

My questions are:

Is this functionality within the scope of WP-Members system. Or should I look at other plugin(s)?

Any tips, pointers or references on how to start implementing this functionality?

Thanks in advance
Tom

http://wordpress.org/plugins/wp-members/