Topic: A few SAE design questions...
Using the SAE movement rules, is it possible to turn if you are moving faster than your thrust? Example, thrust 4 vessel has a speed of 6 and wishes to make a single portside turn and maintain a speed of 4. If I understand the rules correctly, a ship can't turn if it is moving greater than it's thrust value. No wide turns are allowed at high speed?
Not with the basic rules, no. But there is option D.2: Delayed Turns.
What is the design intent behind limiting weapon traits to only three?
The same reason there is a "limit" of three batteries on a ship -- because I said so. 
But like the three-battery limit, this one can be ignored without any real consequence.
Limiting range based traits to only one type?
Because range-based traits don't interact with each other in a predictible fashion -- e.g. Inverted Range Modifiers (x1.4) and Minimum Range (x0.7) don't have a cumulative effectiveness of x0.98 (the product of 1.4 and 0.7). But again, there is an option to "fix" this; C.4.1 Combining Range-Based Traits (in the Imperial Starmada Sourcebook).
Other than running away or disengaging how can a single ship without 360 degree arc coverage (or AFB) defeat fighters that have closed the distance on it? If I understand the rules, the fighters would be able to move after the ship and choose to attack from the blind spot without any retaliation from that ship.
You understand correctly. Which is why, in your example, the ship is screwed.
Seriously -- you'll need other ships to protect your blind spots, or all-around weapons coverage, or AFB, or your own fighters, or something.
If the speed of strikers and seekers is greater than the weapon ranges on a target ship, and the target ship is moving sufficiently slow enough, that ship will most likely never be able to fire defensively at the incoming strikers and seekers, correct? A concept was to have short range point defense weaponry, such as a range 3, 4+ 1/1/1 anti-fighter trait weapon, but this would most likely not have a chance to be used since the strikers and seekers would attack first, before these could shoot, correct?
You'd still be able to use the weapons -- just not until after the fighters' attacks.
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