I think the voice tools will be more interesting for less organized groups like PUGs or smaller guilds (which seems to be the focus group for this project anyways). I cannot imagine that larger guilds and raids are willing to put all eggs in one basket in terms of communication. I know quite a lot of folks who idle on our TS server while playing a different game or just waiting to be asked for a quick instance run.

The guild bank scheme looks much more interesting. Especially since it seems to offer protection at least against gun and run scam. (slowly draining resources might still be possible but its probably pretty difficult if there are several people who can at least check the ins and outs.
I don't think that my guild will use it extensively because we only fund the very basics (flasks for tanks and sometimes pots, otherwise everybody has to look for himself) but I know guilds where this works quite differently and who will be very interested in this feature.

This will be a little bit odd for me and my group. On our realm it is quite common that you don't have raid guilds, but raidgroups. The difference being, that the raiding members are in different guilds "by design", sort of. This has evolved and it's practically impossible to reverse now. It hase become a tradition.

Now with guild banks it will be fun to observe if there is more people willing to change the mindset regarding this issue.

How long will it be until people begin financing and running in-game banks/financial services with Interest rates, etc? I know I could use a 5kg loan, and paying 5500 back over time wouldn't be so bad!

Unless they introduce some combination of:

A) Binding contracts
B) Credit ratings
C) Automatic paycheck withdraw (I take 5% of your AH sales, monster gold drops and vendoring) -I believe Eve did something like this with automatic payments to guild banks
D) Secured collateral loans (Don't pay me back by X date and I get to repossess your epic mount)

I don't see anybody making sizable loans. The default rate would be huge and Blizzard isn't going to enforce it.