As long as you have access to the email address you signed up with, you should be able to go to the login page for your instance and use the "forgot password" option.

Voyager was one of the ones I left behind, albeit not for that reason. I still have it installed on another device, so I checked & you're right - I can't find a preview post option. You can preview just the body of the post while editing it by using the 3-dot menu on the right end of the toolbar to pop up a menu where it's the first option, but that's not the same as seeing the entire post.

I'm currently using Summit, which is pretty good. I know I've had an issue or two with it, but they were so minor that I can't remember what they were ATM. It's very configurable, and definitely has a preview option as the first button on the toolbar.