7zip questions - password and drag and drop

[Snow-Munki]

Hi,

Just installed 7zip and had two simple questions...

1.) How do I password an exisitng zip file ? I know I can right click and add to archive, from here create a password but it isn't 'practical'

2.) I have a few zip files, I want to add more files into it and normally can drag and drop files straight in, doesn't seem to work on 7zip.

Any ideas ?

Thanks.