Q: How does ship turning work? What does the Rotate Speed value mean? For example, SS Venture has 0.3 Rotate Speed, how exactly does it calculate?Using standard mouse controls, your ship will always try to face in the direction of an imaginary line that extends from the center of the ship through your mouse cursor. The rotation speed is how long until the ship rotates from its current orientation to the desired rotation. 0.3 means it will take 0.3 seconds regardless of arc size. This approach allows for fine tuned aiming in small arcs (the ship turns more gently when the mouse is not far from the current rotation), but quick manuevers when swinging to wide arcs (the ship turns rapidly if the mouse moves great distances from current rotation).
Q: What is Thrust Power vs. Max Speed? How do Afterburners work with this?
Thrust is a physics force value applied to your ship while thrusters are active (i.e. while holding down the right mouse button with standard mouse controls). Thrust is largely about accelerating an object with mass. Different ships have fairly different mass values, so a larger thrust value doesn't necessarily equate to a faster ship.
Max Speed is the top limit (units per second) which the game will cap additional Thrust from having an impact. The Max Speed value displayed in the hull upgrade tooltips is the fastest you can go with Afterburners active; it is actually a lower value if your Afterburners are not on.
Afterburners apply a multiplier (usually in the range of 1.3x to 1.7x) to your Thrust Power, and as mentioned previously, raise the Max Speed to the value displayed in the HUD tooltip. This value is probably the single most important value in determining a ship's agility relative to another ship. Typical combat scenarios involve a lot of circling and positioning; this means many rapid acceleration changes in physics terms. Ships with high Afterburner multipliers (e.g. ANT, Angel Fire) will be the most nimble in positioning and evasive manuevers.
Most ships have fairly similar Max Speeds, but more variety in Thrust values. We do this because racing in a straight path is very uncommon in the current capital ships map layout, so we focus our differentiation on battle movement factors.