Some Notes

It's been snowing. (It isn't snowing now, but there is snow on the ground.)
Have you been painting? (You aren't painting now, but there is paint in your hair.)
Have you been running? (You aren't running now, but you are out of breath.)

Why do you think he had the accident?
Why do you think they won the elections?
What do you think the man ate?
What do you think ate the man?
What do you think the best restaurant is?
What do you think is the best restaurant?

Notwithstanding is used with a noun as direct object, so it is correct in this case, as you thought.

Regardless and irrespective are used with of; there is also In spite of, which is what I would say myself in your sentence.

----------------------------------------------------------------

Joe was having a tough time paying his bills. Now he has been laid off his job. He is worse off than before.

John was trying to date a girl who is not very serious about anything, but he never connected with her. He is better off without her.

-----------------------------------------------------------------

"Tidy up my guest room" and "Tidy my guest room up" are both correct.

-----------------------------------------------------------------

One common pattern is that a verb in -ate usually has a noun in -ation (activate ~ activation, sedate ~ sedation, and many more).

One that can is -ness: if in doubt, try adding -ness to adjectives (blueness, strangeness, wetness, awfulness, interestingness).

-------------------------------------------------------------------

Not a sound did she make while hiding in the cupboard.

Never a sound did she make while hiding in the cupboard.

-------------------------------------------------------------------

As my girlfriend said yesterday, she likes apples so I think I should buy some now.

My girlfriend likes apples, as she said yesterday, so I think I should buy some now.
As she said yesterday, my girlfriend likes apples so I think I should buy some now.

------------------------------------------------------------------

He has a discriminating taste in … (whatever). He makes good choices.

In this case (in the report), it is saying that indictments are being issued or applied unfairly and without consideration as to which companies should be indicted.

------------------------------------------------------------------

The subjunctive (keep) remains the same.
"It is necessary that he keep this document secret."
"It was necessary that he keep this document secret."
This is the correct use of the subjunctive in American English.
I have read that the British are more likely to replace the subjunctive with an auxiliary form:
"It is/was necessary that he should keep this document secret."

----------------------------------------------------------------

I study so (that) I won't fail the exam.

I study not to fail the exam.

This implies "I study not to fail the exam but to pass it.

I study to pass the exam. (Common)

I study in order to pass it.

I study not to fail it. (It is ok, but it sounds strange.)

I study so as to pass it.

I study so as not to fail it. (fine!)

----------------------------------------------------------------------

How many marks did you get in Social Science?
How many did you get in Social Science?
What was your score in Social Science?

----------------------------------------------------------------------

Keep the adverb close to the verb. The idiomatic way of saying these two sentences follows:
He quickly built a house out of straw.
They regularly visited one another.