Do these vulnerabilities affect BTC? Is there any unbiased source of security reports on all the various coins?
These are only serial dependent -- ie: A pays B, B pays C. You cannot reorder and still remain valid.
The security of the standard tx is the strength of the public key hash function RIPEMD-160. The security of Pay to Script Hash is finding a valid SHA256 collision with OPCODES.
The witness variants are a new tx format that uses less space (aka segwit).
The attack is simply a Denial of service, an attacker can block a tx. So if A pays B was never included in a block, B could never pay C.