Hey Jay-R,
First, I have edited a bit of your post, because we prefer not to promote different brands and brokers here.
Well, I do not know if they will keep the Metatrader-Demo data that is available now, or it will be replaced with the new one. I am not sure when this will happen, as well. However, use what you have now and manage it later. But do not hurry with a live account, make sure to practice more on Demo.
Regarding more instruments, I think with the new source there will be more instruments. But currently, these ten are fixed, and as far as I know, they use EA to export the data for these instruments automatically.
If you want to trade some other assets, you would need to use the Home key thing and get the data from the broker.
Cheers,
Petko A