Two things.
If you want php files to be opened with an editor open your Windows Explorer, and click on Tools ---> Folder Options. From here you select File Types, select PHP and click on Change, to change the program you want them to open with.
Now about the DL-Edit-UL steps. Well if you want to change files there's only one quicker way I can think of.
Leave all the files for the website on your computer and if you need to edit one, simply open it from your computer, edit it and upload it to the site.
You'll be asked to Overwrite, click Yes.