Regarding your question, I don't have google+ but give this a try. Just long press on the image you want and it should come up with a box to save image or copy, press save image and it will save to your camera roll. I've just tried it on their info page and it worked. Let us know how you go.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.