Portability question

Hello,
I'm am new to the Portable Apps (aka PA) community and I'm looking at the possibilities of the platform.
I wonder if the following usage of the PA is possible ans meaningful.

If I install the PA applications on a USB-stick and I copy the whole PA-directory to a drive of an (not trusted) PC can I use all the installed applications?
I think that will be possible. Or am I wrong?

If I used the PA in that way and I'm done with that (untrusted PC) and I delete that whole PA-directory. Is everything really gone from that PC?
I will have to use a real delete program because a normal Windows-delete will not be enough to really delete the file!

Reason is that a USB-stick is a high-risk to be infected with virus/malware so I use USBdummyProtect to make sure that the stick is always full when I put the stick in a (not trusted) PC.
Now if I can copy the PA-directory to that PC and later delete it I'm sure that no unwanted files can be copied to my USB-stick. But I want to be sure that the personal information that exists in the PA-directories are deleted when I'm finished

Thanks