Thank you so much for all the information in your responses. Nobody here has to spend the time reading and replying to my (long) OP so thank you for time. There's so much info it's difficult for me to respond to each point but I have certainly learned a lot from reading through. I will continue to try to understand how the blockchains work and how transactions are made but I feel its going to take some time before it all sinks in! I'll keep re-reading achow101's part about scripts and look into this further.

As a newbie to it all, I feel its important to properly understand how wallets work and the responses to my OP really have helped. In doing this a lot of other questions can be answered. I did try Jaxx and have accrued a small balance but the security issue that popped up in the news (and, for me, its quite buggy) reduced my confidence in that type of wallet. I don't want to use online wallets so I will just have to 'bite the bullet' and buy a couple of big drives for a RAID 1 array and download the blockchains. I don't really plan on spending my balances, just exchanging until I have enough to let (hopefully) appreciate so eventually I'll probably use paper wallets.   

There's a lot of good info here so I hope others will find these messages and learn from them.

Thank you!