i learned that having 50 to 60 words in a url is ok and having less words is preferable by google. but i would like to know that as i am gonna include keywords in the urls and i am afraid it will increase the length. is it gonna slighlty gonna hurt me? my competitors have 8 characters domain url and keywords length of 13 and my site has 15 character domain url and keywords length of 13 which one will be prefered by google.

i have been working on my link profile for a month now, after learning about 5 step moz methodology i have decided that i would like to change all of the content of my site and taylor it to what my customers need, am i gonna loose all the domain authority if make changes? if it gonna affect, hows that  gonna come out