If you're not leaving the decisions to him, that means working with a director of football. There's no middle ground here, non-football people should not be making any decisions in terms of which players to target. They can and should block transfers if it's not financially viable, but that's not an issue at Manchester United.
Chelsea's team does not have lots of holes in it, the notion itself is absurd. This is a team that will be champions for the second time in three years. Their first XI is very strong, just as it was 2 seasons back. As for your other points;
1) Absolutely ridiculous to state he is "by far the best manager" in a league that has, among others, a man who's won a Champions League with Porto, a treble with Inter and league titles everywhere he went. Let's see again in 10 years time. For now there's no point having this discussion. To be fair, the past record argument can be at times lazy. football moves quickly, typically in cycles of effectiveness. For example, Jose hasn't made a CL final in 7 years whilst his 1st 7 seasons, there were 2 CL victories. Capello has won more than anyone in this league but he isn't the best or even near it. He has a better record though. in Jose 1st 7 years he had won 6 league titles. in the last 7 years its 2. so from 2 CL victories and 6 league titles in the 1st half of your career to 0 CL and 2 league titles in the latter half. it is not unfeasible that Conte is currently, as in right now, the better coach tactically.
2) This is undoubtedly a massive factor.
3) Wasted money on average players? Such as Ibrahimovich who is among the top scorers in the league this season? Or Mkhitaryan who was a standout player in a strong Bundesliga team? Or Bailley who was relatively cheap and impressed early on before he started picking up some injuries? These transfers were absolutely necessary and have certainly made a difference, even if Mkhitaryan and to a certain extent Pogba have not really shown their true colours yet. Our squad was a mess, you can't solve that in a single transfer window. I'm more or less confident we're on the right track though.