Can I use a company bank account to pay for expenses such as staff meals and personal expenses?

You can use a company bank account for all purchases but are only able to claim a tax deduction for business expenses. 

For staff meals if you are providing drinks including alcohol and refreshments in social settings, this is recognised as entertainment and without registering FBT, entertainment expenses are non-deductible.

If you are providing light refreshments and meals in the office or workspace, this is more likely to be recognised as staff amenities and is tax-deductible.
Visit the Australian Taxation Office for more information on entertainment expenses and fringe benefits tax.