Hi Jenxstar,
I'm sorry to hear that you are encountering this problem. I have not been able to locate your account based on the information available to me, but I definitely recognize both of the API errors you mentioned because I have seen eBay return them for other sellers as well.
The first API error you mentioned *should* mean that eBay has made a change to their international selling agreement and, upon receiving that error, you should have been able to post your listings successfully after going to the URL in the error message and accepting the new international selling agreement.
The second API error that you received is related to a new policy eBay UK has implemented recently that is preventing new sellers from using third party listing tools (such as Auctiva) to post or revise their items until they have met the requirements listed in the message, but I have not seen that message returned in error before.
Based on what you described, it really sounds like eBay's system generated both of these API messages in error and, unless there is some information I am missing, I am inclined to agree that there must be a technical problem on the eBay side of things that is causing these errors to be generated inappropriately.
Although I am uncertain if there will be anything more I can do to help you out with this, if you reply to the support case you opened about this situation and request to speak to me by name, I'll be happy to review your account and see if I can find anything new.
-Mike