We can see that a couple of hotfix packages are available for our Office 2013 product family, called April 2014 CU. We know as well that we have issues when SharePoint 2013 has SP1 installed separately. Unfortunately we have not yet the full-server package April 2014 CU for SharePoint 2013 and also not an answer available what happens with SP1. Therefore I would like to give you an overview.

SP1:
We read in kb article 2817429 and 2817439:

We have recently uncovered an issue with this Service Pack 1 package that may prevent customers who have Service Pack 1 from deploying future public or cumulative updates. As a precautionary measure, we have deactivated the download page until a new package is published.

As of today we have no news, but we know that as soon as possible we get the final information, you will read it at several places.

SP1 issues are only a subject of discussion when you do not have installed SharePoint 2013 including SP1, also called Slipstreamed installation. Same is valid for OWAS.

April 2014 CU:
Our full-server packages (SharePoint Server and Foundation) are not yet available and therefore you could install only “sub-packages”. From support perspective we are always suggesting to install full-server packages, but in case you need an important April 2014 CU hotfix, just for your info.

SharePoint contains not only SharePoint components and therefore the following list may not exhaustive.

General information you can find here: http://support.microsoft.com/kb/2953733

Access Server Download Link
Contains fixes when SQL Server 2014 will be used.

OWAS 2013 has an own kb article:
2863899    Description of the Office Web Apps Server 2013 hotfix package (Wacserver-x-none.msp): April 8, 2014
http://support.microsoft.com/kb/2863899
For this package you need to have a SlipStream installation of OWAS2013 including SP1 or you can install it on top of any other former CU.

SharePoint Server 2013 Oserver package
2760265    Description of the SharePoint Server 2013 hotfix package (Oserver-x-none.msp): April 8, 2014
http://support.microsoft.com/kb/2760265

SharePoint 2013 / Word Server
2768332    Description of the SharePoint Server 2013 hotfix package (Wdsrv-x-none.msp): April 8, 2014
http://support.microsoft.com/kb/2768332

SharePoint Server 2013 Coreserver package
2863887    Description of the SharePoint Server 2013 hotfix package (Coreserver-x-none.msp; Projectserverwfe-x-none.msp): April 8, 2014
http://support.microsoft.com/kb/2863887

SharePoint Server 2013 Client Components package
2863895    Description of the SharePoint Server 2013 Client Components SDK hotfix package (Spdevsdk-x-none.msp): April 8, 2014
http://support.microsoft.com/kb/2863895

SQL Server 2014:
We will support SQL Server 2014 with SharePoint Server 2013 but we need April 2014 CU and also SP1 installed.

RTM of SQL Server 2014 and when SharePoint 2013 will be supported: http://blogs.technet.com/b/wbaer/archive/2014/03/21/sql-server-2014-and-sharepoint-server-2013.aspx

Using SQL Server 2014 Reporting Server (SSRS) features together with SharePoint 2013? Check more here: http://technet.microsoft.com/en-us/library/gg492257(v=sql.120).aspx

Without an April 2014 full-server package for SharePoint Server 2013 we cannot say yet that it will be supported with all available features. We also need updated information in our TechNet that we now support SQL Server 2014, but it should be available as soon all information are collected.