Hello again Tenneille,
A good reference for fiberglass repairs is here:
Where exactly are the gel coat cracks? Can you post pics? Generally, unless gel coat cracks are accompanied by a pronounced bend in the surface, the underlying fiberglass is not damaged. Next, to identify underlying damage, you need to view the backside of the fiberglass looking for cracks or separation. If you find it, then repair by bending the surface back into place, properly supporting it, then adding at least 3 layers of fiberglass mat coating each layer with resin. After supporting structures are in place and any underlying fiberglass cracks have been repairing, then you can repair gel coat cracks if desired. This is done by grinding (i.e., with a small v shaped grinding head) a very small groove along the crack, then filling with thickened resin or body filler.
Regarding the cracks on the upper half driver side, first thing to do is add support between the lower and upper cabinet. There should be a support on the left side next to the sink.
Regarding cracks around the door, again I would first fix the source of the problem, apparently the broken frame (and from your other thread, the threshold). The other structures supporting the door opening are the closet wall and the curved square metal tubing to the right of the door as you enter. Make sure all of these supporting structures are in place and firmly attached.
Regarding the screw holes in the frame, I simply used larger self tapping screws and washers. This worked.