Incorrect. Federal law makes it illegal to record a phone/electronic communication unless at least one party to the communication consents. That's a very different thing.
There's no conflict. Federal law says it's illegal unless at least one party consents. Maryland law says its illegal unless all parties consent. You must comply with both. If you only comply the federal law, then you aren't violating the federal law, but you're violating the state law. States are allowed to enact laws that are stricter than federal law.
Not really sure what you're asking here, but I'm sure that one-party and all-party consent laws are violated every day without any consequence.
That's silly. It's a little like saying that, if I'm traveling at 50mph in a 50mph zone and no one is around and I briefly accelerate to 51mph and no one sees me and no harm results, then I haven't violated the law against speeding.
While your comment about the practical aspect of things is well-taken, what law do you think exists on this issue that says no violation occurs if the recording is "never used in any way (other than to jog the memory of the person who made the recording)"?
All telephone communications are part of interstate commerce -- even those that take place between persons in the same state. If Congress wanted, it constitutionally could preempt state laws on this issue.

