Pro User, Question about the best practices of models

Hello , i am new to cursor .

1.If my context is short, how much difference does it make to use gpt-4o-mini or cursor-small versus the premium models?
Should I use gpt-4o-mini or cursor-small for short contexts?

2.Is there a big difference between the Premium models Claude 3.5 Haiku and Claude 3.5 Sonnet?