You use their bones to move them through frames to make motion data.
I would suggest looking through tutorials if you're a beginner, I've provided one link below in the 'Related Links' section.
use pmd editor you can get it on youtube or vpvp wiki
.mqo is for metasequioa, Metasequioa is a program that can be use to create MMD models.
Miku MIku Dance (MMD) is a 3D animating programm., witch is used to make models dance, pictures or even to make short movies.
PMD Editor is an application for MMD (Miku Miku Dance) where you can edit the models
you need pmd editor (and several tutorials XD)
if you go on google you can search for the mmd models which u will use and the motions (dances) they will do. I suggest going on deviantart.com for those. Then go on youtube and lookup tutorials on mmd.
If you are using the regular MMD (miku miku dance) you cant but if you are using a multi model edition of MMD you can download new models.
yes its a common bug
You can use google images or make your own
To use Miku Miku Dance (MMD), start by downloading the software from a reliable source and installing it on your computer. Next, import a model by downloading MMD-compatible models and placing them in the "Model" folder within the MMD directory. You can then load your model, add animations, and manipulate its movements using the interface. Finally, you can create scenes, adjust camera angles, and render your animation or video for sharing.
You can get them on Youtube, Nico Nico Douga, VPVP wiki, Deviantart and many more places just look and you'll find what you need.
If you are using the MMD multi model edition they should be in your MMD[insert version of MMD you are using] → UserFile → Model