I've had problems with add and remove as well.
Now I use yum to manage packages, it resolves conflicts and downloads the latest packages.
It is best on a broadband connection, FedoraNEWS has help on yum:
HOWTO: Use Yum
Using Mirrors:
HOWTO: How to increase yum speed
FedoraNEWS Homepage
To see vnc related packages use:
yum list vnc*
To install vnc viewer use:
yum install vnc
To update all your packages use:
yum update
I hope this helps with add/remove.
For mount adding the lazy '-l' option may help; my drives seem to be busy for no apparent reason as well. Lazy un-mount and closing unused apps often works, it also allows the console to be closed while running umount in the background.
I hope this helps.