Measurement is defined in the share repurchase plan itself, and the common formulation is a percentage of NAV as of the last day of the prior quarter or the average over that period, which means a markdown that lands in the current quarter shrinks next quarter's window rather than this one's. Read the exact sentence in your document, because a plan measured on trailing NAV and one measured on current NAV behave very differently in a falling market, and neither is standard enough to assume.
On suspension, most plans give the board full discretion to modify, suspend or terminate on notice, with no restart trigger you can enforce. The board's stated reasons usually include liquidity, adverse market conditions, and legal or regulatory constraints, which is broad enough to cover almost anything. If you want a restart obligation you would have to find a sponsor that wrote one, and they are rare.
Your proration math is right in shape. The part that bites harder is that queues aren't always carried forward automatically. Some plans require you to resubmit each quarter, so an investor who misses a submission window drops out of the line entirely and rejoins at the back. Check whether unfulfilled requests roll or lapse.
The other thing worth pricing is what a redemption wave does to the remaining holders. Meeting redemptions in size means selling assets or drawing a credit line, and the assets that sell fastest are usually the good ones. So the investors who stay can end up holding a lower quality portfolio with more debt on it. That risk isn't in the repurchase plan language at all, it shows up in the leverage covenants and the credit facility terms. Anything about how the plan applies to your specific tax or estate situation is a question for your own counsel.
