this is really not as hard as you may think..
there are a couple of ways to handle the subject.. one way is to use a bunch of if's and stuff to calculate the direction the ship and bullets are going to use.. I've seen it done before, but I think it makes it all very complex, and not to mention somewhat "clumpsy"..
the way I usually go about this sort of thing, is by using sine and cosine to calculate the ship and bullet coordinates..
you might want to read up on vector mathematics if you want more detail, but basically what I do is this.
Every object I work with (ie. ship and bullets) have atleast a x and y coord, and also an angle and speed.
the wayt I calculate stuff is by adding a vector, based on the speed and angle, to the x and y coord. This is easily done like this (example for the ship):
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xvector = Cos(ship\angle * RADMultiplier) * ship\speed
yvector = Sin(ship\angle * RADMultiplier) * ship\speed
ship\x = ship\x + xvector
ship\y = ship\y + yvector
notice the RADMultiplier constant.. it is a value you have to multiply to every sin and cos calculations in your program, since sin() and cos() in PB works with 400 degree circles.. (and we usually use 360 deg.)
this constant is 3.141593 / 180..
now, to move the ship, we do the following.. for turning, we only add or subtract the angle of the ship (remember to only use a value between 0 and 360) according to the turn left and right buttons.
to move the ship, you just add to the ship speed (when the key for accelleration is pressed)..
I hope you understood the basics of the calculations above...
Now graphics-wise, I'd suggest you draw a ship, and then make rotated copies if it in one or several graphic file(s).. you then load the files for example into an array of, say 36 files.. (this is to make the rotations smooth).. then to show the right graphics on screen, you just get the current ship angle, and divide it by 10, then show the sprite in that arraynumber..
another solution is to make a series of points, and draw lines between them (to manually draw the ship), but then you'd have to also calculate the new position of each point every frame, so that they ship points also rotate in accordance with the ship angle..
simple, huh..
If you want, I'm sure I can knock up an example for you on the ship movement, when I have som spare time...
on the following: