The Medical request will come to you here in the US then you can send the Medicals forms to her if you want to have it done from the DMP in your native country, although keep in mind that sometimes it delay the process because of family members completing medicals in different countries.
Same thing with passport request, it will come to you here in the US, when it comes, you need to submit your passport here, you cannot change and send her to your native country embassy for visa stamping, it must be submitted for visa stamping at one place where you applied.
She can send her passport to you if she can't come, however sending passport out of some countries is illegal, you should check the laws in your country on sending passport to US.
Same thing with passport request, it will come to you here in the US, when it comes, you need to submit your passport here, you cannot change and send her to your native country embassy for visa stamping, it must be submitted for visa stamping at one place where you applied.
She can send her passport to you if she can't come, however sending passport out of some countries is illegal, you should check the laws in your country on sending passport to US.