1. Lowe's options are surplus value so there's little doubt that they'd get picked up. Us talking about him as a trade target is pretty proof positive that if the Rays don't want to pay him the 8 figures they can get something for their trouble.
2. IMO, Vlad + Castillo I don't think *requires* Nico or Busch. Castillo has little surplus value and the point of trading him is about freeing up money more than making a specific acquisition. If the Jays decide to trade away Vlad they're signaling a step back in 2025(so Nico makes no sense), and while it's possible they may want Busch I'm guessing they'd want to gamble on upside more so something like Alcantara may be preferred(and 1 year of Vlad at 25 million is unlikely to get 2 pieces of that caliber).
3. Short answer, yes. Assuming you don't give up a locked in roster player/guaranteed contract in the trades, you can trade for Castillo, Vlad, and Lowe, then use 25 million on a FA C and a couple relievers and basically be where you are now. You may have to make a marginal cost decision like running with an NRI/prospect roster spot instead of Wisdom's 3+ million, but that's the level of sacrifice we're talking about. However, if you're trading for Vlad and not trading away Nico, the need for trading real assets for Lowe loses some luster.