All odds are American. Each section feeds the next; everything recalculates as you type. Editing a section never changes the one above it.
One row per market. Add sides within a row; add markets below.
One row per priced market above, filled in from its first side and its vig. Edit either field to override it.
One row per leg. A single leg is simply that bet, and still carries through to the stake. Legs are assumed independent - a correlated parlay is worth more than this says.
The first row's true odds come from the combined parlay price above. Add stake copies the last row's prices and carries over its bankroll less the half Kelly bet - the chain does not drive added rows.