Basically, you do not want to change the workflow by making them do everything via the webapp. They will go nuts. If you can consider making Excel file upload and download part of the process, it'll make the transition much smoother and less frightening.

PHP also has modules to handle Excel files. On top of that, an XSLX file (not plain XSL) is actually an XML file. You can extract the XML content and parse that via an XML parser.

Oh, I didn’t know that, that is very interesting. I have some commitments for a few hours, but I’ll be back to discuss :) thank you very much!

I'm actually in HK Time, so it's 1:27 AM when I post this. It won't be a live chat, but we should go over the project a little so you're not going to hit brick walls.

For any process changes, a new system is hard to implement, because old habits die hard. You want the new system to be as transparent to the user as possible, and also have the option to implement changes in phases.

One of the best thing to do right now is to connect with the Excel guy and see if there's anything that you can help with. Even using Google Spreadsheet and GAS (Google Apps Script) will be a smoother transition than giving them a webapp.

Personally I wouldn't really worry about your credibility with non-technical people. Just help out to the level that they want you to help out and don't see it as a personal loss. The word-press issue just smells like Steve isn't a team player. Very Type-A behavior. I would just steer clear of him unless you like dealing with people like that. Him cancelling the hosting service either means he's stupid or he's disrespectful. Sometimes you just can't fix them.

Now, a cool trick for "reading" the raw data in an Excel file. Rename the XLSX file extension (not XSL files, just XSLX files), change it from XSLX to ZIP. Double click it. You will see a bunch of folders and XML data. You can edit the XML, and as long as it is properly formatted, you can rename the file from ZIP back to XSLX and open it in Excel.