With ECC 7.0, you are upgrading to SAP Business Suite 7 Innovations 2013 (SAP BS 7 i2013). This has implications for everything in your landscape. The easiest description of this can be found in the Planning Guide: SAP Business Suite Landscape Implementation - Technical Planning Guide. (SMP login required).
The table that covers SAP BS 7 i2013 is on page 20.
You will need to upgrade PI to 7.30, 7.31 or 7.40. The same holds true for BI, and the SAP Portal if you have those installed. If you haven't already upgraded Solution Manager to 7.1, you should, because the modeling tools are slightly better the more up to date you get. (Hint: You'll probably want to go to 7.4 across the board for consistency in maintenance and to get the longest possible support for your new version so you don't have to upgrade again soon.)
You must have your ENTIRE landscape modeled correctly in order to be successful with an upgrade. If you haven't done an upgrade recently, the new tool, Software Update Manager or SUM, has changed the game entirely. Solution Manager is now integral to the process. There's no point in trying to figure out versions on your own for each of the components. You are much better off devoting SIGNIFICANT effort to get your modeling correct in Solution Manager. This is easier said than done, so be prepared to do a lot of research do a lot of trial and error if you don't have an experienced consultant to guide you.
I suggest you start by reading everything that Wolf Hengevoss has ever written as that is your best source of SLD and LMDB information. His stuff can be found in the IT Management group. I suggest starting with the blogs found at System Landscape Directory (SLD) and More on System Landscape Directory .
Once you get your modeling in the SLD and LMDB (Solution Manager) correct, the Maintenance Optimizer (Solution Manager) will help you get everything to the correct and compatible versions.
I hope this helps!
Best regards,
--Tom