the someone else approached in hi-vis

[Alexey86]

It was a smooth and pleasant journey to Brighton, although on arrival the icy conductor didn’t mess about waiting for someone on the platform and instead used the onboard ramps, perhaps to save time, despite the fact they are mean to use the station ramps.
After a lovely day in Brighton I headed back to the station for my return journey to Hastings at 6.45pm. It was very busy with barely any staff on hand. At the barrier, I was told to find another member of staff who could help me. Eventually the someone else approached in hi-vis. I told him I needed the next train for Hastings. Hi-vis was at least friendly. “Get on the Ashford International,” he told me. “I’ll try and grab the ramp but it’s going in the next five minutes.”
(https://www.theguardian.com/commentisfree/2016/aug/01/southern-rail-service-disabled-passengers)

Questions:
1) Does the someone else sound natural to you?
2) Would it make sense and be natural if I changed the sentence to Eventually one of the staff in hi-vis approached me or Eventually some man/woman in hi-vis approached me?
3) Would it make sense and be natural if I changed the preceded sentence to I was told to find someone else from the staff who could help me without changing the following sentence?
4) Why member of staff? Shouldn't it be member of the staff?

 

[Skrej]

Does the someone else sound natural to you?

It's natural, but not extremely common. It's just a way of referring to an unknown person. Notice that the same person is subsequently referred to as 'hi-vis' - a reference to the high visibility safety shirt (or vest) the person is wearing. It could be considered either slightly humorous or slightly degrading, depending on context.

2) Would it make sense and be natural if I changed the sentence to Eventually one of the staff approached in hi-vis?

Yes, but it loses the humorous/ironic sense.

3) Would it make sense and be natural if I changed the preceding sentence to I was told to find someone else from the staff who could help me?

Yes, but again it loses the intended effect.

4) Why member of staff? Shouldn't it be member of the staff?

"Member of staff" is a BrE term, (AmE =staff member), so I'll leave this one for a BrE speaker to comment on.

 

[Alexey86]

It's just a way of referring to an unknown person.

How will the meaning change if I omit the?
Eventually someone else approached in hi-vis.

 

[Skrej]

It loses the intended ironic or humorous effect, and become just a normal grammatical sentence.

"Someone" is a pronoun. We don't normally use articles with pronouns. By adding 'the' it essentially makes 'someone' into a noun (i.e. "the person"). Again, this is an attempt at sarcasm or humor.

Note that this is very subtle, advanced language manipulation by a native speaker. It's not something I would recommend a learner try to emulate. It's also not very common. Part of the humor stems from the fact that it's rarely done.

Note also that the author makes her living by writing and performing spoken word, so she's writing more than a mere newspaper article. She's using specific language to evoke an emotional response to raise awareness to the issues she and others in wheelchairs face trying to use the train system, along with what she considers substandard service.

 

[Tdol]

4) Why member of staff? Shouldn't it be member of the staff?

Nope