1. Small hands and piano playing?

This mindset is incorrect.

Children
Many piano students have small hands due to their young age and ongoing development. Children grow and develop rapidly. Through active daily practice, their hands get exercise, which accelerates hand development.

Adults
For adults who have passed the growth stage, their hands won't grow any larger. However, there's no need to lose hope. The key to learning piano lies in practice! Finding suitable practice methods, mastering techniques, scheduling practice time, and engaging in extensive practice can enhance hand flexibility. While small hands may lack span, finger strength and agility can compensate for this.

2. Are larger hands better for playing the piano?

Certainly not. Everything has a limit.

Let's shed some light on the advantages of different hand types!
Long fingers: Facilitate playing wide octave chords; enable more accurate execution of large interval jumps.
Short fingers: Offer greater control over tone production at the fingertips; facilitate faster playing.
Slender fingers: Provide nimble and clean articulation, ideal for agile ornamentation.
Thick fingers: Contribute to a fuller, more emotionally expressive musical sound.
Soft fingers: Enhance musical expression and lyricism, particularly for conveying subtle emotions.

(Finger Strengthene)
In reality, hand size and piano proficiency are not inherently correlated; each has its own advantages. The most crucial aspect of learning piano is practice. Mastering the instrument renders all other factors insignificant!