HI All 
Barry
the upgrade options are something that’s been discussed at length in the Carrara forum, and, (I think) there’s still no solution.
(As far as I know) it’s an issue with how the new store works.
You can contact Daz and they can sort out an upgrade for you, but,...
unless it’s something you Need to do right now,.. I’d wait a while, until there’s an announcement on C8.5, because there’s usually a sale / special offer thing, at that time to entice existing users to upgrade,.. and at that point I think they’ll NEED to have an upgrade option in the store.
As for C7, ..Daz should be able to sort that out for you, since it was available (free) on a Mag coverdisk.
there should also be no problem upgrading to C8,... I’s technically not an “Upgrade”.. It’s a completely different program, (C8 pro is also 64 bit) ..so it’s not required to have C7 installed.. to install C8.

Jacob,
Yes, you can write with particles, and create lot’s of random ambient patterns. plus, particles can also be carrara objects like fog or fire, or custom objects you’ve made, like tomato’s 
do a you tube search for “Carrara Particles”
Age of Armour, and Dimension Theory have some great particle examples and tut’s
