I don't know specifically about figs, but internode length is often a response to light - things grown in lower light intensities often have longer, 'leggy' internodes, and those grown in high light often have very short internodes.
As to the buds higher on a branch breaking and growing first, that's a hormonal response and also gives the plant a better chance of growing its leaves in more intense light for better growth. The more light falling on the leaves, the more photosynthesis, the more ps, the more carbs produced for subsequent growth.
Without 'positioning' their leaves in adequate light, most plants don't grow as well so their hormonal systems are geared to 'getting' them adequate light they need - be it via increasing internode length or having only the top, higher buds breaking to produce leaves.
And of course things such as genetics, environment (heat, moisture, wind, etc) and adequate mineral nutrition (soil, fertilizer) play roles too.