Salesforce - Setup filtering contacts by radius from location

We have a small non-profit organization. We have a Salesforce account (Enterprise Edition) with Non-profit Starter Pack 3.0 (NPSP3) installed with only about 1000 contacts. We hired a SF developer to help us setup the account for our needs several years ago. For the most part, the system is working well for us. We occasionally have issues come up that we need help with. We would appreciate it if you would consider submitting a bid to help us resolve this issue:

FILTERING CONTACTS BY RADIUS FROM LOCATION
We would like to be able to filter contacts based on their distance from a location. We have entered mailing addresses in SF for each contact we want to filter. If we "Enable Maps" using this setting (https://i.imgur.com/SHbLr3M.png) we can view maps for each contact. But, we are not able to do a radius search. I have tried using the Mailing Address and "within" option under Contacts View (https://i.imgur.com/rjLwXBV.png) but no contacts are displayed.

What I would like to be able to do:
1. View a list of contacts by radius from location (Latitude/Longitude is fine) using the Contacts View
2. Our previous SF developer made it possible for us to select contacts using a custom filter string for complex queries that aren't possible in Contacts View. For example, "npe5__Organization__r.Type = 'College - Christian' AND Primary_Contact_for_Org__c = True AND npe5__Status__c = 'Current' AND npe5__Organization__r.Date_Follow_Up_After__c <= TODAY AND npe5__Organization__r.Do_not_follow_up__c = False". I would like help with creating a similar string for selecting contacts within a radius.
To resolve the issues, I would like to schedule a meeting(s) with SF developer via web conference (VOIP with screen sharing) between the hours of 9-5pm EST (GMT-5). I would like the SF developer to walk me through the changes I need to make in order to resolve this issue.

If you submit a proposal, please include:
A. Your experience resolving similar issues
B. A general idea of how long you think it would take to resolve and what would need to be done
C. Your spoken English proficiency level

Thank you for your consideration.