You do need access to an account server. You can use TTN's account server on https://account.thethingsnetwork.org. We're still doing quite some development on this, but as soon as the API is stable, we'll define a specification for this account server so that you can implement your own.
This could be caused by a number of things. For example if you have a single-channel gateway closeby (#140), if you're not in Europe (#119 and #120) or some other unknown issue. Talk to me on Slack tomorrow (CEST) and I can try to help you.
That's not possible yet, but it's on our todo list.
Only use confirmed uplink if you really need it. It eats downlink capacity.
That's not possible yet, but it's on our todo list.