If I cast Ride the Wind, and move a unit to Abandoned Hall, does the unit get +1?

Yes. When you cast Ride the Wind to move a unit to Abandoned Hall, that unit does get +1 [S] from Abandoned Hall's triggered ability.

Here's why the timing works:

1. Ride the Wind resolves and moves the unit to Abandoned Hall (readying it).
2. Only after the spell's resolution completes does the "When a player plays a spell" trigger on Abandoned Hall check in. Since your unit arrived during step 1, it is present at Abandoned Hall and is a valid target for the buff.
3. The trigger goes on the chain and resolves, giving the unit +1 [S].

The key point is that Abandoned Hall's trigger fires after the spell finishes resolving — not while it's still on the chain — so the unit is already there to receive the bonus.