You are not specifically assigned to any pool account anymore, and upvotes on all 11 accounts (10 voting accounts plus this commenting account) all contribute to your upvoting bonuses.
We have compiled the most helpful readings here: https://steemit.com/steembasicincome/@steembasicincome/helpful-sbi-resources
As for the inflection point of larger votes and consistent votes, what does an estimate approximate?
The estimates we give when people check their status are the estimate for their next post only. Our system adapts automatically to changes in subscription level, posting frequency, and STEEM price, so those estimates are not accurate outside of a very limited time window.
In addition, the purchase of STEEM at the present moment is a precious opportunity to stack tokens, yet does this weakened price require more STEEM to achieve the income at given thresholds?
Each SBI unit is effectively backed by the voting capability of ~2 SP (dependent on sustainability metrics). When the value of STEEM falls, it takes a bit more to attain target levels. We deliver a relatively consistent return if measured in STEEM, but it's subject to exchange risks when converted into any other currency.
The upvote minimums are regularly recalculated and based on STU because the reward potocol has a final STU check before payout. We recommend subscribing with at least $10 worth of STEEM (currently about 30) to get daily upvotes and a subscription of at least 40 SBI units unlocks special access in our Discord (including some on-demand boosts from this commenting account).