Baited Hook

Yes, as killing the unit is part of the effect, not a cost, so it's a target declared when the ability is put on the chain.

"Kill a friendly unit" comes after the ":" in Baited Hook's activated ability, so it's the first instruction of the effect rather than part of the cost — an activated ability's cost is everything before the ":", and its effect is everything after.^[377.1] Because it isn't a cost, the friendly unit is a normal target, chosen and declared as the ability is put on the chain.^{[355.7][355.8]} This is the opposite of cards like Sacrifice, where "kill a friendly unit" is stated as an additional cost and is therefore excluded from targeting entirely.^{[355.10.c][355.10.c.1]}

Since the unit is targeted rather than paid as a cost, opponents get a normal opportunity to react before Baited Hook's ability resolves, just like with any other targeted ability.^[359.3.c] Later in the same ability, "up to 1 more than the killed unit" references the unit affected by the earlier "kill" instruction, making the two linked instructions.^[359.3.e.14] Because the unit has already moved to the trash by the time this later instruction checks it, the ability looks back at the unit's characteristics as they were immediately before it changed zones.^[359.3.e.13]

The unit can't be killed, and no unit can be banished from the top 5, since nothing can satisfy a might comparison against a null value.

If the friendly unit is no longer a legal target when the ability resolves — for example, if it was returned to its owner's hand in response — it is unaffected by the ability's "kill" instruction.^{[359.3.e.2][359.3.e.5]} Because the unit was never killed, any information the ability checks about it, including its might, returns null.^[359.3.e.12] "Banish a unit with might up to 1 more than the killed unit" can never be satisfied against a null might, so no unit can be chosen from among the top 5 cards, even though you still look at them. "Then recycle the rest" is unaffected by this, since it isn't tied to the killed unit's might — you still recycle every card you looked at that wasn't banished.

After, even though it's finalized first — finalization proceeds in the order items were appended to the chain, but resolution proceeds in the opposite order, newest item first.

Baited Hook's ability resolves in its entirety without interruption,^[354.3] so both the killed unit's Deathknell trigger and the unit it later banishes and plays get appended to the chain as pending items during that same resolution, with the Deathknell appended first. Once Baited Hook's ability finishes, those pending items are finalized in that same order — Deathknell first — but the chain then resolves newest-first, so anything appended after the Deathknell, including the banished unit's own triggers, resolves before it does. The step-by-step below spells this out.

Killing Ruined Rex — whose Deathknell reads "Deal 4 to an enemy unit" — as an example: