I searched online and people said that it is normal to get a brown spot in blue eyes. Also, some green eyes and gray eyes are easy to have such spots. They are caused by variations in freckling, mole counts, and hair and skin tone. But commonly, it is harmless.
Well, I think you might get floaters is due to the degernerative changes of the vitreous humour. Floaters have different size, including dots and lines. Sometimes you try to catch them, you will find it is difficult to stare at them. However, if you ignore it, it will appear. Many reasons can cause flloaters. Generally speaking, changes in the vitreous humour is the main reason. To tell you the truth, I also has this problem for couple of years. It only bothers me at times, so if the condition is not serious, you can ignore it. If not, you can accet surgery.
According to your description, it is possible that your eyes get palpebral fissure because of long-term exposure to the untraviolet rays, or this is possible caused by the degeneration of the optical connective tissues, which is is often seen among the groups of adults and those who usually work in the outdoors. A topo-logadectomy can be helpful in getting rid of the brown spots in your eyes. In some cases, the brown spots in your eyes can also be caused by fundus hemorrhage, then you can take a laser theropy to treat the choroidal neovascularization which is quite effective.