Is Abel eligible to claim a deduction for a proportion of running expenses in relation to the home office space?

Abel is a full-time staff member of ‘The Wildlife Room’ pet store company.

In addition to his daytime work, Abel is required by his employer to work from home on a regular basis. This work from home consists entirely of managing the extensive paperwork of the business and maintaining the software program used to run the business. The work from home does not involve seeing any clients and Abel does not sell any pets from his home.  Abel does not install any signage to suggest from the street front that the office is present. Abel also continues to use the laptop and phone that his employer provides.
No clients or colleagues visit the home or home office and there is no available space for car parking if clients were to visit the premises.
Abel works from home 5 days per week. Abel uses the office space for his employment only
and no personal effects are stored in the ‘second bedroom’ except for a piano that remains in one corner.
For the year ended 30 June 2021, Abel advises you that his home electricity expense totalled $3,000 and that the house insurance bill was $1,500 and the council rates were $3,000. Abel also advises you that he paid $15,000 in home mortgage interest and that his water rates totalled $1,600.
Required:
a) Is Abel eligible to claim a deduction for a proportion of occupancy expenses in
relation to the home office space?
b) Is Abel eligible to claim a deduction for a proportion of running expenses in
relation to the home office space?
c) What impact does the home office space have on the CGT main residence
exemption?
d) How would your answer to (a) change if Abel was self-employed and did see clients at his home from time to time but still only used his ‘second bedroom’ for his
business activities?