Hi Kap,
Here's my comments on your two requests:
1. Although opening two configs simultaneously would be useful, this isn't really possible with the way Workflow is made. Workflow is designed to only allow one active configuration at a time, and in order to implement that, we'd have to put heavy restrictions on a second opened config, such as not allowing to send it, not allowing debugging, etc... A lot of trouble for something that although cool, isn't really needed in most situations, and hasn't been requested much in several years.
This problem can be worked around by keeping a changelog updated with the changes. Or, instead of having multiples copies of your configs, have multiple inactive copies of your processes, so that this way, you keep an history of the work that has been done to processes. (this suggestion may not be that good if you have a lot of processes though...)
2. There is a limit to just how much we could implement this. Unlike Design, Workflow can include external or custom resources, such as scripts, or custom plugins, that can make use of the variables, but because they're not really part of the software, we wouldn't be able to affect them. (and since it's generally more advanced stuff, we wouldn't necessarely WANT to have the application automatically change the code to "help" us, then end up breaking something in the process...)
There is also an easy workaround: Workflow configs are really XML files, and you can open them with a Text editor. Meaning that you can do a Search and Replace for the old variable name, and replace it by the new one if you want to. But as I've mentionned above, there might still be stuff that won't have been affected, or affected the wrong way, so I would still recommend double-checking the result.
Regards,
Raphaël Lalonde Lefebvre