4. This is a controversial issue, with people who are actually in the business, people like Allan (not Allan necessarily, people LIKE Allan) stating quite plainly that Day 1 DLC is stuff that would not be in the base game. If you ever catch them saying otherwise, tell me, because then I'll be happy to blame them for it. But we have no proof.
I understand the cynicism towards this though, especially if consumer trust is shattered. You'll likely not find anyone (anywhere) going "We intentionally ripped this out for the sole purpose of selling it as DLC" even if that were 100% the truth.
The tricky part of DLC is that it's difficult to really prove one way or another. That is, unless you're actually present at the decision making process, it's hard to definitively state "this content would not exist without DLC" or "This content would have existed without DLC, but because DLC is a concept it has been intentionally removed in order to be monetized."
Even if a DLC concept is created during the earliest stages of preproduction for the base game, it still can't really be said if that concept would or would not be in the game if a DLC model didn't exist. Which makes it tricky.
DLC does provide an additional source of revenue, and it does provide a sense justification for allocating resources. If the budget is expected to be entirely used in one aspect, additional funding can be justified to be applied if the expected return lets it be. This expected return can be in additional sales of the base game, or through other revenue streams, for example.
I find it a grey and muddy matter that is very difficult to get an assessment of from the outside. inXile is pretty proud of their "no DLC" type of stance, but at the same time refusing to do any sort of DLC on principle may result in not delivering content that they'd like to deliver, and may result in fans not getting as much content in a game universe that they enjoy that they otherwise would not get.
Now the optics come down to Day One DLC, which is obviously a subset of DLC. This is about examining the line of critical mass for a DLC release schedules, because the inverse correlation of DLC success vs. time since launch is very strong.