Firefox Portable

Hello. I don't want to update my main Firefox installation yet because several add-ons I use are legacy without replacements. But I'd like to segue to FF 57 and instead of creating a new Portable Apps directory it would be nice to use a 2nd profile installation in my regular PA directory for the transition. I know I can use the beta but betas are betas.

Have a nice day!

Is it ipossible to launch the "Desktop Firefox" and Portable Firefox (52.2.0) in the same time?
If I start "Desktop Firefox" then I start Portable Firefox I get an error message pop up:
"Another instance of Firefox is already running. Please close other instances of Firefox before launching Mozilla Firefox, Portable Edition"
Is there a solution?

I have Firefox v57.0 "installed" as a portable app. In the "App" folder there is a "Firefox" folder and a "Firefox64" folder. I only ever use the 64-bit version so is it possible to completely delete the "Firefox" folder? It's kind of strange in a way. The "Firefox" folder contains 113 files. The "Firefox64" folder contains 112 files. What is the extra file in the "Firefox" folder?

Using Firefox 57 with syncing via Dropbox. After the browser restarting even on the same device its customization settings are reset to defaults and the Firefox Account Sync is logged off (so re-login is needed after each restart). How to resolve this issue? Thanks!

https://www.mozilla.org/en-US/firefox/

If Firefox portable is closed and I open a cmd.exe window (or run a batch file) with something like this: FirefoxPortable.exe www.mozilla.com
there won't be any problem.

How could one open 2 Firefoxes at the same time?

This message appears when trying it (saying, another instance is already running):
[IMG]https://i.imgur.com/PufvSpP.png[/IMG]

Where could I get the last version of FF to get the add ons working again?

I would like to be able to use my legacy extensions. I will keep using the latest FF, but occasionally need data from my old "scrapbook" extension which doesn't work with FF 57