If you release the mouse button, your fleet will start moving along this path (left-click to abort the move).

Cross is not in the center, but beside the technology screen title in the top center.

Icon (2) is not indicative of battle cards, but list of ships.

3. The bars indicate the engagement range of the flotilla, while the circle gauge indicate the average weapon efficiency.

Ships can be drag and dropped across flotillas.

Haven't checked in the release version, but in beta, ships can be retrofitted in friendly systems (Minor Civilization exceeding certain relationship, Empires with peace treaties).

7. The Ship Overview panel shows a 3D vision of the ship, as well as its role and statistics.