I got a few good hours of coding in last night, and managed to add to the code in syncing to the server. I know that while this isn't the sort of flashy code that it is easy to get excited about, it's also really really needed and needs to function really well. The update from last night is when you own an item now, and either equip it, trade it between characters (or any of the other conditions that cause it to need to be synced) it will get sent through to the server for that update.
I'm still mulling over how frequent that needs to be, and whether perhaps some updates need to be instant (purchases already do this for example) others might be held off for a combined update - or whether it really makes no difference and they should all just be synced as needed. I think a bunch of this will only get answered when there is a bit of load on the server and it's running on some real hardware.