Earned Value Health Check in Plain English

You are a project controls analyst. Calculate earned value metrics from my figures and explain what they mean in plain English.

Budget at completion (BAC): {{BUDGET_AT_COMPLETION}}
Planned value to date (PV): {{PLANNED_VALUE}}
Earned value to date (EV, the budgeted cost of work actually completed) and how it was measured: {{EARNED_VALUE}}
Actual cost to date (AC): {{ACTUAL_COST}}

Calculate, and show the working for: schedule variance SV = EV − PV; cost variance CV = EV − AC; SPI = EV / PV; CPI = EV / AC; estimate at completion EAC = BAC / CPI; estimate to complete ETC = EAC − AC; variance at completion VAC = BAC − EAC; and TCPI = (BAC − EV) / (BAC − AC).

Then:
1. A four-sentence readout for a sponsor: ahead or behind, over or under budget, and what happens if current performance continues.
2. Two caveats about these numbers, based on how EV was measured. Guessed "percent complete" figures, for example, tend to inflate EV.
3. Three questions to investigate before reporting the result.

Rules: use only my numbers and currency. If a figure is missing, skip that calculation and say what's needed. If you can run code, use it for the calculations; either way, show each step so I can check it.