The "Format Patch" default external tool already should provide the ability to create patches.

In the first case, develop tracks origin/develop, in the second one it doesn't. How this can be improved in SmartGit?

If you already have to edit the code, why not use copy-paste now to get the achieved effect?

Could you please explain the difference between "squash commits" and "fixup into (previous commit)"? Thanks in advance.

Each view, e.g. "Branches", "Commits", "Changes" is a tab. You can use drag and drop to rearrange them.

In the above screenshot part which colors of the "commit connector lines" you would use for the message text?

You already can do a lot of those commands in the Outgoing or Journal view. What commands you are missing - please create a new topic for each missing command.