Does depreciation affect cash flow in a positive or negative manner? From a net present value perspective,

Question:

Does depreciation affect cash flow in a positive or negative manner? From a perspective, why is accelerated depreciation preferable? Is it acceptable to utilize one depreciation method for tax purposes and another for financial reporting purposes? Which method is relevant for determining project cash flows?
Net Present Value
What is NPV? The net present value is an important tool for capital budgeting decision to assess that an investment in a project is worthwhile or not? The net present value of a project is calculated before taking up the investment decision at...