I just purchased this car and I love it but there are a couple of problems.

First, my keys fit into the trunk lock but don't open the trunk. I have to open it from below the drivers seat.

Second, I hate that the passenger side door automatically locks. Every time we park I have to unlock it to get out. How can I change that?

 

If key will not "turn" trunk key cylinder then either the cylinder is woren out or it has been changed
If on the other hand cylinder does turn but just not open, then the linkage has come apart, possible #20... http://www.hondaautomotiveparts.com/...gry5=TRUNK+LID 94

 

Hi, I haven't found an answer to the automatic locking problem - my 05 Civic SI (standard) randomly locks, sometimes when driving and sometimes after I've opened my door and before I'm able to open the back door. Other than this annoyance, it's a great car.

 

your door lock is most likely a bcm (body control module) issue, or a door lock actuator. either way take to the dealer they can find the issue.