Some good points well made. I'll respond to a few of them.
Boris's successes as Mayor of London were largely due to having a capable team around him. The more competent ministers in previous governments realised that Brexit was a bad idea, and by various routes this led to them no longer being part of the present government. Most of the current cabinet strike me as intellectual midgets not well suited to the tasks they have committed to.
The intellectual ability of ministers isn't really that important for delivery. Their principal function is PR (and taking the flak when things go wrong). So long as there is a decent team of Civil Servants and advisors in place the ability of the Minister is unimportant. If we could move on past our obsession with judging people on the basis of their performance in front of a TV camera it would help a great deal. (and I suspect JC and I would agree on that point)
So the key issue is how effectively can Boris bring in the right people behind the scenes as he did as London Mayor. Possibly some of the right people were reluctant to take on jobs before the election because their tenure would be very uncertain. With (probably) a 4.4 year clear run, and a majority that allows relatively unimpeded implementation I think appointments in non-political roles will be highly sought after.
The short and long term damage to the economy makes it harder to pay for and implement the government's promises.
Skipping past any debate over the extent and duration of any possible damage, I think the answer here is the one the left have been championing for the last 10 years. The ability of Governments to borrow and spend (on construction) in difficult economic times has been a tool used many times in the past. Historically low interest rates and a squeeze on spending in the recent past possibly puts the Government in a good position to use this lever wisely. In addition, with the terrible interest rates paid to savers I would not be surprised if there is some form of
Boris Bond that offers savers the opportunity to invest in rebuilding our infrastructure. It might cost a bit more than borrowing on the market, but would deliver additional benefits for (potential) voters.
And if it all goes horribly wrong, he can point out that Labour's plan was to borrow and spend wildly, and the left have been demanding it for a decade, so the country would have been as bad, if not worse off, if a Labour Government was in charge instead.
There is going to be a huge row over Scottish independence and quite possibly NI will seek to join the Republic. From the point of view of a government of England and Wales, that is more distraction.
I think the possible way out on this is to tell Sturgeon she needs to develop a fully worked out and costed plan for Scottish independence, including preliminary discussion with the UK Government and EU over issues such as border controls, currency, debt and EU accession.
Then have a free vote in the Commons, on the basis of the plan, whether it should be put to the people in a (binding?) referendum. Sturgeon can hardly refuse this when she has been banging on for the last 4 years about how the 2016 referendum isn't valid because it wasn't conducted on the basis of a worked-through plan.
I would also expect a large number of English Conservative MPs to abstain in the vote (if it happens). The number of MPs required to block the referendum would be quite small, and tactically it would place Labour and the LibDems in a very difficult position if it is their votes that either allow or block IndyRef2.
I would also add into the mix whether voters in the other three countries of the Union should also get to vote on Scotland's future, as leaving the Union could impact on them as well. For example, if the deal with Scotland didn't involve them taking on a fair share of UK debt then it would only be fair if English, Welsh and NI voters were able to veto the deal.