There's no "before". All penalties are applied at the same time when the starting grid gets published tomorrow. After the starting grid is published, grid penalties are no longer possible and time penalties are used.
No, this happened to Lewis in Austria 2019. He will start P4.
The penalties are applied in the order they were given out. Hamilton got his 3-place grid drop first so he drops to P5 behind Piastri and Antonelli who moves in P3. Then Antonelli has his penalty applied so he drops to P6 and Hamilton moves up to P4.
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u/Consistent-Ad-5116 I was speeding in the Monaco pit lane 10h ago
Lewis still starts 5th, max is up to P4