Governments
most certainly do step in to stop deals from happening, and even if a deal is not stopped outright, it's not uncommon for them to attach additional terms to a deal.
However, the circumstances around which intervention happens is centered on aspects such as national security (
Broadcom/Qualcomm), running up against existing regulations (
Disney/Fox), privacy, competition (
both of which popped up in the Google/Fitbit deal), or similar concerns.
It does not arise due to consumer or investor sentiment.
Yes, they can't legally lay out plans for a company they don't own yet. I wouldn't expect a full rundown thought, even though I'd like them being as clear as possible. However I think MS will talk about the plans of announced games like Starfield. But don't expect something like "Bethesda games will never be ported to XY" imo.
Yes they can; that would be an integration plan, which begins far before ownership. Proper execution of such a plan is actually a
common lynchpin on which deals hinge. Follow through happens with ownership; a company can choose to reveal a good bit of what they want to do on deal
announcement; and they (or might not) might reveal more once the deal is assured - there is no law preventing planning.