looking in to moving to Japan to start a new life, where do I begin?

So my marine buddy has contact with a realtor in yokosuka that ill be getting in touch with soon, so im wondering where exactly to i start to get things in motion. Never so much as had the thought of moving there and havent even been there but just been put into a position where I dont have any choice but to relocate.

how long does the citizenship process usually take?

is it possible to open a Japanese bank account and convert my usd to yen?

how exactly would getting a phone plan work in japan?

how difficult exactly would it be for a foreigner to find a decent job that i could sustain myself on?( for reference i have a tattoo on each hand 1 on my left forearm and a smaller one on my right forearm)

how much would it cost to take a Japanese language class?

would my previous work experience in America matter at all?

have around 9 months to get things moving any help is appreciated