Private Blockchain Deployment

I am developing a POC using Ethereum. We were thinking to deploy it first in public blockchain using Infura but as it is small DApp and dynamic rates of Ether we go for private blockchain.
1. We should carry this approach and go for private blockchain or rollback to the public blockchain using Infura.

2. For private blockchain, we need at least two servers or we can do it with only 1 server.

3. Also, if we do it with only 1 server will it be decentralized?