As for whether or not to reduce OCF for acquisition costs, you shouldn't because those costs are already taken out in calculation of net income.
Maybe I'm misunderstanding this part. Do you mean once the acquirer consolidates the acquiree's operating business? Because as far as I know, there's no hit to income for the cost of the acquisition (save for some restricting charges or the like). It's mostly the balance sheet which is affected, and then costs are capitalized in future periods.
What do you mean by acquisition related costs? If you mean hiring an investment banker, doing due diligence, and costs integrating an acquired company, it does hit net income via SG&A.
Right but if the company is acquired for say $100m, it's not like net income is reduced by $100m the next year. It's only the operating pieces and any one-off acquisition-related charges (like restructuring, lawyer fees, etc) that hit net income.
The acq costs from the Investing section of the CF statement don't reduce Net Income by the same amount.