Is icloud free?

Yes.

The only thing you'd ever have to pay for is to purchase additional storage, if you ever wanted more.

but what if you are home all the time

what does being at home have to do with any thing

No, it isn't. Only the first tiny 5GB is free. After that, it's $$$$$ all the way....

You do understand you can delete the back up and and then continue using the free 5GB to make current back ups.

Yes, of course, although that means I am limited to a total of 5GB (unless I pay for extra). My little iPhone has no room to spare - 16GB of music, books, files, maps, e-tickets etc. With my Macbook, I also have a full 160GB of files with which I work. So I would like at least 64GB extra to to play with if I move (as I am considering) to an iPad.

Fortunately, I have found a possible solution to my conundrum with wifi HDD, and have attempted to start a discussion to get more info.

Yes except for buy more storage.