Do I have to download the cd/dvd every time to upgrade?
If you are not familiar with portage then the best route is to wait till the next release is available. You can upgrade through portage and layman only if you know what you are doing. The installer has several options for you. Always backup your files before doing anything. My personal opinion, backup, fresh install, restore backup. Equo is going to make this easier in the future. You will be able to take the mini and upgrade to a full dvd version also. More information will come on this. If you are familiar with the system then you can keep up to date via portage and layman.