I just installed SP 2013 SP1 and I want to make sure latest CU is in place before I run config wizard. Will the April 2015 CU completes all the issues from SP1 to now? Are there any other CU or Hotfix I need to install to make sure servers are up to date?
This CU includes all SharePoint 2013 fixes released since SP1, That's mean you all set and your farm is up to date.
For SharePoint foundation, You don't need to install the SharePoint Foundation separately if you have Server installed and Install the Server CU.
So you all set here as April CU for server include all hot fixes till SP1 and also include the foundation fixes.
Follow the below blogs for up to date information. April 2015 CU for SharePoint 2013 has been released (updated April 15th)