Thank you for the detailed feedback. Here are some answers/suggestion to some of your questions:
The reinforce fleet can be done in multiple ways. The typical way is to select a specific set of factories or planets that have factories and right click the focus planet (or the fleet there). This sets a "rally" point so that all produced ships will go there. I typically rally to my flagship in that fleet so if it moves the rallied ships will follow it.
I also typically keep my flagship(s), factory planets, and planets I'm attacking in the bookmark window to the left. Click the flagships/factory planets/target planet and drag them to the left. This grants you several important UI and strategic advantages but specific to your question, it allows you to instantly select your factory for production without moving the camera and right clicking your flagship (or target planet) in the bookmark window to set the rally point (again without moving the camera).
You can also setup control groups, and a few other tricks but that should be sufficient for now. We also have some new stuff coming in a build or two that will help manage the tactical side of things a lot better.