ROE and FCFE from Income Statement

I just did a problem and was asked to calculate ROE (for a sustainable growth rate) and FCFE from an income statement + a bit of extra information. The answer explanations used different calculations than expected.

ROE = NI / Ending Equity

I see this formula multiple ways. The curriculum defines it as NI / Average Equity in the FRA section - which was also possible in this problem since we had two years of data.

Is it safe to assume we use NI / Ending Equity when calculating a sustainable growth rate (unless told otherwise)?

FCFE

I calculated FCFE starting with NI. The answer started with EBITDA and used an assumed tax rate of 35% which was stated a few paragraphs later. The actual tax rate in the income statement was ~32% so my answer was off starting from NI.

Is it safe to assume we need to start with a pre-tax measure (EBIT or EBITDA) to calculate free cash flow if we are given a tax rate that is not equal to the actual tax rate?

I was hoping there was somewhere in the curriculum that someone could point me to that makes this clear.

Any thoughts on this? I assume the answer to both questions is yes but I don’t feel the curriculum is very clear on these points.