Hosting ashx file from developer generated solution

Dear all,

Need help regarding customization.  I recently received a solution from an in-house .NET developer who claims the best way to pass/save data to a non-SP database hosting outside the farm is to use JQuery/JavaScript-->Ajax-->web handler file ashx at 14 hive.  Then this custom installed ashx file will relays this web service calls to the remote web service hosting at another server for calculation.  Also, the developer generates an event receiver dll file (farm scope) to handle the communication between SharePoint lists and the remote database.  Bascially the business requirements is to have users from different groups enter shift personnel data and display daily so management has a daily head count (used to handle this in a big Excel file).  The solution works and meets the business requirements.  Yet the solution architecture design concerns me since I know we will migrate to 2013 within the next 6 months.  At this point I only have very limited knowledge about .NET codes and this type of external connection customization I have couple questions need your help:

1. For a SharePoint Farm Administrator what's the general guidelines/governance to handle external connections?  I have a list to collect any external dependances to the sites I know of.  Yet I don't own all contents.  Is there a guideline I can ask content owners to follow so when know what to do when disaster happens?  Our governance plan is blank for this topic at this point.

2. ashx file is in the OOB block list.  It must have a reason for that.  Does anybody know why? 

3. Does anybody have any other suggestions regarding how this could work in other ways?  I know we should use BCS but the developers doesn't know how.  Yet I know there must be an easier way for this, at least I don't have to live with this dll when I migrate to 2013. 

Thanks in advance for any help.

Sally