I have a PhD in Political Science. At what rank will I probably be entering in the army?

Without much detail, this sounds like "I am in the Army and looking for a wife, and I love you very much scam'. These are African males looking to get access to your bank account, or have you send them money as a short term loan for any number of made up excuses. I only noticed your 2018 question today, so I hope you didn't fall for it. Quora.com is full of similar stories.

I knew a career major in the Gurkha Regiment who remained single until the day he died. He worked for M.O.D. and Ford afterwards.

yes. it is sad that the Secretary of the Navy names ships for political purpose and does not follow traditional naming rules. that class of ship was supposed to named for small towns

No as you have already signed up with another branch of the military

I've heard it's very strict. I myself live right off of base and was Married and I walked to the fort every day. That way army had no say in what I was doing. Period .

Use whatever the Army issues to you.

No.

An O-1 has 0-2 years of experience. An E-9 would have 15-30 years. the E-9 typically "trains" and guides the O-1 in leadership especially how to care for his or her troops. Every successful military leader will tell you they owe much to their Chiefs and Sergeants who showed them the ropes.

it depends on your re-enlistment code in your record. contact your nearest recruiter.

Do you like sleeping in the mud or in a hot tent - join the Army.
If you want an air conditioned bed on a clean ship with hot showers - Go Navy.

certainly not. in fact servicemembers can get absentee ballots from their state.
however they are banned from political campaign activities and
must abstain from "any active part" in political campaigns in accordance with the Hatch Act.