As first a trusted user and then a moderator I can say there is a lot of options a moderator can do to solve many issues, but a moderator should not be confused or even related with the privilege status of trusted user.
As a trusted user you have gained enough reputation to have the trust of the community (I mean 20K points is a lot) with all the questions/answers you have provided the community with. With this new title you can do many things a normal user can not like the ones mentioned in the link.
I mention to not compare trusted user and moderator status as both differ in some points. To be a moderator you actually do not need a lot of reputation, what you need is the trust of the community, which is in part gained by reputation, but part gained by how you create questions, answer questions and give out helpful advices.
Gaining the trusted user status grants the same "trust" as a moderator to a certain degree. This does not mean a moderator is less trusted, it just means they have gained the moderator status by their deeds on the site and how the community views the moderator. On the other hand, the trusted user has accomplished that status by all the hard work without the need to become a moderator, which would add a lot of work (Trust me.. A LOT!) to the user if he/she would try to get that position.
So to answer each question individually:
Does this mean that moderators are not trusted users?
To be a moderator you need a certain amount of reputation, but more importantly, to have the trust and a positive image for the community to give you the vote in the first place. As mentioned above, having good questions/answers and helping out the community is the way to accomplish this. To become a moderator means that the community trusts you to make the right decisions and you have shown to be a good candidate for it.
Does this imply that a foundation of trust is not necessary to obtain access to moderator tools?
I believe, the base of a moderator is trust. Although the highest privilege is named "Trusted User", it should not imply that users with 19999 reputation points or below are not to be trusted. Several of the mods that work on a day by day basis on the site have less than 20K. Even Mark Shuttleworth has less than 20K and I am pretty sure, most users in this community, might have a little bit, tiny, small amount of trust on this guy. So yeah, a foundation of trust to the community is needed, but is gained by doing some of the points mentioned above.
So don't be discourage or confused by the title of the privilege. I know it confuses one when compared to a moderator but as I mentioned, trust is the way to go on both cases.