The Higuain story is something that's been widely reported, while the Wayne Rooney angle, from what we can see, is essentially the same as this story from earlier today, where Alisher Usmanov urged the club to make the signing, saying it would be good for both Rooney and Arsenal (and, in our opinion, Manchester United, although in fairness that's nothing to do with him.)
There are two things to note here. The first is that Usmanov could be playing games with the board, dropping out a huge name as a potential signing to get the fans whipped up and force them into spending. The second is that it's the Daily Mail.
Addressing the latter point first, the Daily Mail seems to have a poor reputation among some people, but that stems a bit too much from the front pages. They're not Transfer Tavern - their stories are sourced and credit as good as any other newspaper, and the fact that Tony Evans is the head football writer at The Times tells you all you need to know about how distinct the back pages of a paper can be from the front.
The Usmanov point is something that we have no way of knowing, of course, so we'll have to see. It'll be interesting to see what happens with Rooney - talk has gone cold lately, but that's expected, since United will want to make sure they're getting the right players in before letting him leave. There's not much new here, but the fact the Mail are willing to put it on their back page (along with the amusingly-insistent "we're not joking") suggests this rumour isn't total nonsense.