Does Polygon Edge support Smart Contracts?
Yes. Polygon Edge networks are Ethereum compatible blockchains, so Smart Contracts that are deployable on Ethereum, are also deployable on Polygon Edge chains.
Can you update the staking contract logic for PoS after deployment?
For now, after you have started the PoS network, you cannot change the staking contract logic, as it is part of the genesis file. So you cannot, for example, change the minimum/maximum number of validators. What you can do is stake or unstake, to add or remove validators.