Explaination some BSC swap issue -- 2

Job ID: 32218725

Budget: $30 – $250 USD

Contract A: https://bscscan.com/tx/0xc3128ee9613bb630be326b4802f80b74e6e7a934c4a87aa2bd2e361ce5db295b
Contract B: https://bscscan.com/tx/0x1adb6c2af83a62959968b69262ad1807a99dc8cfc32c70e75df6d5e2e1895ba4
Contract B: https://bscscan.com/tx/0x91228598f2bc473f46aed8214e617866070457b70beb03cce39ee785d2ea360f

1. What is the difference btw two above contracts? Contract A takes one "Transfer" to complete a swap. But B takes two "Transfer"?
2. Which RPC endpoint provider is the best in "up to date" block information? Lowest delay time? Such as Moralist,...??
3. What is the mechanism of contract B - "Self destruct"?
4. Please give me the good implementation of the pancake library for swapping( low gas price )?
Related categories: Blockchain Solidity Smart Contracts