Politically and practically, I'd suggest you use Windows and their tooling to start with. When you're getting started they'll likely need to help you get setup and that's going to be difficult for them if you're using other tools. Later on, you can make more informed decisions about switching tools after getting familiar with their applications.

If they run production on Windows as well, there are likely bits of the software that won't be cross-platform (file paths, encodings are common ones). We have a mix at our shop (Windows, OSX and Linux) and I think we only get away with it due to everyone knowing what to avoid (through experience). We still step on each other's toes occasionally. It wouldn't look good if you spent a lot of time at the start fixing things just to get it to work on your platform.

I think Sublime has a vim mode (or plugin) that should give you similar keybindings and it has panes a bit like vim.

As to getting back to PHP, some good links have already been posted. Get up to date on Composer and PHPUnit, look at whatever framework they're using and build some demo apps on it.