The solution to your first question will probably require a script. Not sure what would do the trick tho.
There is no easy answer to your second question. The Chrono Trigger sprites have more individual frames of animation than RM uses. The default frames are just Walking Animations. The additional sprites can be completely separate sprite sheets, which don't need to have walk animations. They can contain additional poses for your characters. There are event buttons that allow you to change an event or characters sprite during an evented process.
Now finding resources for chrono trigger sprites is as simple as googling. The sprite sheets that are available on several websites will need to be edited to fit RM formats. XP is 4 x 4, and VX+ is 4 x 3. The character graphics themselves dont need to be edited, just copy out the relevant walking animations that you need, and put others into their own Pose sprite sheets. For example, you can have a Marle sprite sheet where she just walks around. Then to do cutscenes, swap out her event image and use a different sprite sheet that holds her poses.
Building different custom sprites that have the poses you are referring to is our Holy Grail, and just as elusive. There are several free Sprite Generators for RM floating around, but to the best of my knowledge, none of them have additional poses other than just default walking animations. Ive heard of some japanese programs that I think might be able to do poses, but those are not free, and there was no information about those programs supporting additional poses.