If you do an LLC or sole propretiership, and you and your spouse file jointly then yes those write offs would be applicable to her income.
Business Income - expenses = what you pay taxes on.
If you spend more then you make then those would be losses, I think you can only lose money for 3 years though.
Business related client entertainment/meals (1/2 deductible)
Car travel - 51 cents a mile
Any legit business expense.
Just make sure to have separate bank accounts and don't co-mingle stuff. Also not a bad idea to seek some advice from a CPA
Use something like waveaccounting.com
For free online accounting
Freshbooks.com for invoicing
Good luck, but don't plan to not being profitable. Get out there and Rock It! Make money, think successful, be successful!