Can I deduct expenses for working from home since March of 2020. Expenses for having to set up a home office?

Sorry---W-2 employees cannot deduct expenses for working from home.  Job-related expenses were eliminated as a deduction for W-2 employees by the tax laws that changed for 2018 and beyond.  Your state tax laws might be different.

https://ttlc.intuit.com/questions/4482873-which-federal-tax-deductions-have-been-suspended-by-tax-reform

Yes, start up costs are deductible. You may deduct qualified start-up costs you paid or incurred while setting up your business up to $50,000.  It can either be deducted in the year you open the business up to $ 5,000 and amortized the remaining for 15 years.