If I'm planning on helping Yes Man and create and independent Vegas, should I deliver the Platinum Chip to Mr. House or not? Will things be more difficult at the end as Yes Man suggests if I do?

Give House the Chip. House is the only one who truly knows how the Chip works and what capabilities it can unlock. I think giving him the chip is probably one of the only ways you can upgrade the Securitrons which you need in the independent path. To answer the difficulty question, there is a terminal near the Secret door which makes the Securitrons friendly, rendering the difficulty moot.