score:4
Q1: Answer ‘0’ and explain in the application/cover letter that your family will be staying with you during their visit. If you do not own your accommodation, provide proof that you are allowed to have guests eg rental agreement, letter from landlord
Q2: Answer ‘yes’ if your wife is not paying all the costs of the trip herself. Your wife should submit her bank statements. See Should I submit bank statements when applying for a UK Visa? What do they say about me?
This guidance may help https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/589168/VAF1-guidance.pdf