Hi there and welcome HOME.
Okay if you get errors with portage / kuroo:
There is likely a program that is masked and is blocking the install or 2 programs 1 blocking another from installing.
Click on LOG on the left side in kuroo and look for wha tis causing the problem.
as root in terminal " emerge --pretend @@@@ " where the @@@@ is replaced with the name of the package you wish to install.
This will list several options and info but also in red the blocked / blocking software / program.
Then using kuroo select it and uninstall if not needed or "emerge --unmerge @@@@@ "
I have seen this in 3.3 and 3.4 loop avahi is needed as well as mdnsresponder (so try to avoid messing with avahi / mdnsresponder) , ati blocks something as well as hplip.
If a program is masked say something like nvidia is masked and you need it , then edit /etc/make.conf or using kuroo o the top bar select kuroo and settings and the "USE" option just add nvidia or remove the " - " in front of nvidia.
IE: -nvidia -gtk qt3 qt4
New = nvidia -gtk qt3 qt4
The minus means do not install , I hate gnome so -gnome for me.
The pretend option as root in terminal is very good and helpfull , like for firefox
"emerge -uD mozilla-firefox --pretend"
and this will list the update and deep dependancy's that is needed for it to work propperly.
PS> note the gnome it lists , I have no gnome so I can ignore the gnome part.
Hope this helps.