LawPH

Hello, I am very new to this subreddit but tried lurking to some questions similar to this, and I unfortunately have no idea how legally changing name works here, so I hope my questions to be answered!

Situation: I want to change my middle name and surname into my mother's maiden middle name and surname.

Background: I am a born Filipino, raised by a single parent. I would like to instead use my mother's maiden middle and surname because my dad is an abusive deadbeat who abandoned us as a family when I was really young. The last I heard about him according to word of the mouth was that he was busy raising his second family and unfortunately, my mother never got the chance to take legal action against my dad since he died from cancer. My reason for changing into my mom's maiden name is that I only want to be associated with my mom and her side of the family through all of my success and failures in life since they're the ones who raised me. I'm also planning on finishing my MA and perhaps PhD someday, so when people address me by my title, I also want for them to call me by my mother's surname. Basically, I don't want to be tied down to my dad's surname until the day I die since he contributed nothing but misery in our lives.

Questions:

1. Based from some responses on other people here, one of the most strongest reason to argue in legally changing names is due to trauma (e.g. being bullied because of your name), and without going further to personal details of my life, I find my experience with my dad traumatic, so I want to know if I have to be evaluated by an expert for this to count as trauma?

2. Based on my background, how high is my chance to legally change to my mom's maiden surname?

3. How much is it to change names legally?

4. How long does this entire process take?