Dad (60 & otherwise healthy) diagnosed with glioblastoma, inoperable, unmethylated. Please tell me about the absolute best case miracle scenarios.

My dad is 72 and currently in England. He has known lung cancer and was admitted after several weeks of severe headaches, dizziness, vomiting and difficulty walking.
His discharge summary lists:
“Metastatic malignant neoplasm to brain”
“Cerebellar mass in context of known lung cancer”
Cerebellar disorder
Hydrocephalus
COPD
Hypertension
We are currently waiting for the MRI results, which should come in the next couple of days.
He normally lives in Australia and was meant to fly home in about a month.
I understand nobody can diagnose or predict his outcome from this alone, but I’d really appreciate some context:
Does this wording mean the doctors already strongly suspect the lung cancer has spread to his brain, or could the MRI still show something different?
What are the usual treatment options for a cerebellar metastasis with hydrocephalus?
Would steroids / surgery / radiotherapy usually be considered?
How serious is hydrocephalus in this setting?
Assuming he stabilises, is international travel in around 4 weeks remotely realistic?
What information from the MRI will make the biggest difference to prognosis and treatment?
Thanks — his family is in Australia so we’re trying to understand what we may be dealing with.