So do I understand correct if this is what I do:
1 - I download the software
2 - Use it to copy images from my camera to my computer
3 - Import to LR
Or wil it automatically be in LR?
I'm not sure since, as noted in the thread I linked to previously, I prefer to work with RAW files (in LR4), not DNGs. But I would copy the RAW files from the camera to the computer first, then convert them to DNG format, and then import the DNGs into LR.
If I use iPhoto etc to import, then I have to import again to be abel to use them i LR
I also don't use iPhoto, but I would guess that's how it would work.
Will I loose image qality or metadata?
Again, DNGs are supposedly lossless, so you shouldn't lose any image quality. I'm not sure about metadata, tho. But if you do as above and copy the RAW files from the camera before converting them, the metadata should still be in the (original) RAW files (on the camera) if the conversion strips it out.
Is the LR4 update worth the money?
Depends on whether or not you use the new features.