Concerning the "WARNING: Checkpoint is too old. Wait for the blockchain to download, or notify developers of the issue" message.

Everyone can ignore this message as it causes no issues to functionality of the wallet.

This will be gone in the upcoming release of Silk(SLK) version 1.0.1.0

Spencer Lievens has just committed a pull request - https://github.com/SilkNetwork/Silk-Core/pull/29

Which fixes this issue - https://github.com/SilkNetwork/Silk-Core/issues/28