Based on your photos rhinoplasty will be better option for you. Instead of having the two operations performed separately at different times, you should consult a board certified surgeon and decide on the procedure and operation. Then everything will be better for you.
Yes they can dissolve completely but it depends on the product that is being used. Some fillers will last less than a year while others will last up to 5 years. Permanent fillers have also been used but are largely unpopular.
I was taught the art of using Silikon-1000 to correct nasal irregularities during my fellowship. When used properly, you can safely get completely natural, permanent results.
Since Silikon-1000 is a permanent filler, your results depend entirely on the technique, and expertise of your physician....