Hi,
You must specify a bidding strategy at a campaign level, so removing the campaign's bidding strategy is not an option.
I took a look at your campaign and ad groups, and it looks like all of the overrides at the ad group level are overriding using the same attributes, e.g., all overrides are for Target CPA (just like the campaign), only with one of two different bids. In that case, have you considered splitting the campaign by bidding strategy? In other words, have one campaign with all ad groups with strategy+default bid A, and another with strategy+default bid B.
Regarding your other question on errors, please check out our
Partial Failure guide, which explains how errors are handled in detail and covers your configuration options around error handling.
Thanks,
Josh, AdWords API Team