Hello yuzuCA
As long as the business expenses are ordinary and neccessary for your business, then they are deductlible to your business, which will reduce your business profit, thus reducing your taxable income.
Yes, you can hire your children as employees. The salary and wages you pay them as a business expence, which in turn reduces your business profit, thus reducing your taxable income. If your children are under the age of 18, then their wages are not subject to FICA taxes (Medicare and Social Security) and FUTA taxes. Here is an article detailing more about this.
Business related travel as well as retirement contributions by self-employed tax payer are deductible as well.
With regard to business expenses, as long as it is ordinary and neccessary, and you are able to justify the reason for the expense, you can take advantage of the deduction for business purposes.
I hope this helps