The root certificates are for BIP70 payment requests which can be signed with an X.509 certificate. Those certificates are SSL certificates, and they are signed by the root certificates. Specifically, I think the root certificates are just the ones that come with your OS.
Yet another security concern. Didn't know that. Thanks.
If you dont use BIP70 payments, e.g. dont click the link on a bitpay payment, bust just copy the data yourself it does not affect you AFAIK.
Any idea what is this 'Non-canonical signature' about and why 'S value is unnecessarily high'?
Its related to the malleability attack[1]. Newer version no longer relay modified transactions to lower the impact of the attack. Once all nodes are updated it will be impossible.
[1]
https://en.bitcoin.it/wiki/Transaction_Malleability