On bitcoin DLC oracles:

What are oracles? 
Oracles are just price servers. They figure out the price of an asset based on querying a set of exchanges and attest to the price, so that bitcoin smart contracts, like Lava, can leverage the price data.

How are bitcoin oracles different than oracles in Ethereum? 
In Ethereum, oracles attest to the price on-chain every block. This is expensive because oracles have to make a txn per attestation, and it introduces miner extracted value as miners can censor or potentially re-org oracle attestations to make profit. In bitcoin, oracles don’t have to attest on-chain because DLCs are off-chain contracts that settle on-chain. This is a massive unlock because not only does it reduce fees, it also solves one of the biggest problems in Ethereum (oracle MEV) and significantly improves reliability.

How private are bitcoin oracles? 
Bitcoin oracles are just price servers and so they don’t know anything about the contracts using their data. This is also an added benefit of bitcoin oracles vs Ethereum oracles as in Ethereum oracles have full visibility on contracts using their data.

Can I choose my own oracles per contract? 
Yes, if you read the multi-oracle DLC spec (link below), you can learn that this is possible. Another benefit of bitcoin smart contracts is that each contract can have its own set of oracles. For example on Lava one contract can have a different set of oracles than another. This also does not exist in Ethereum, and it is another massive unlock for users and optionality.

How can I learn about the default oracle implementation? 
At Lava, we’ve written the oracle implementation for bitcoin oracles. You can read it, contribute, or even run your own setup. The link is below.