1. It will definitely not boost the economy. Unlike a natural disaster, terrorist attack or war, an epidemic doesn't destroy infrastructure, so that's the small positive. But the stoppage of essentially all economic activity is comparable to a full scale depression coming from social, political or pure financial reasons. Some industries will definitely suffer more, such as the ones dependant on people travelling (airlines, and well, really all transportation except public transportation provided by city governments; hotels; tourist attractions) or on events (obviously concerts, stage and movie theaters; sports; but also organizers of parties and of conferences). Some will suffer less: Big Retail, and the makers of products now in high demand, like the toilet paper we're being recommended to eat for prevention and treatment. But there is no industry where the lost income will not mean bankrupt enterprises, firings, and lower investment. The people now without an income, either by losing their jobs or by having to close their business, will strain the economy until all of those jobs and businesses can be recovered. How long that takes is now unpredictable, but it will not be immediate. The epidemic will deplete private savings all over the world, and because of both the increased expenses in health and in security (having to deploy police and military forces) and the reduction in taxes collected (from lower economic activity), governments will not be in a position to Keynes their countries' way out either. Hiero mentions that older people, most likely to die from Covid, tend more to be net tax takers. But the epidemic is not a Logan's Run world. Although some places are seriously abandoning their oldest patients to die off, all treatments, including those on younger people with low fatality rates, are expensive. So the savings there are low. The assumption that with fewer older people some social programs will be less strained, leaving more resources for other things, while correct, is also misleading. How many casualties have there been? [I seriously don't know, and I don't really feel like finding out, because overall I don't think that's an important piece of data for me to know. It won't change what I have to do in the face of the epidemic.] I think that's like 100 thousand. And that's worldwide, all countries combined. And that's also all ages combined. Obviously there will be more casualties; but even so, more people will die of malaria even this year. (To keep it in the "infectious disease" category. I could mention non infectious disease. Or accidental and violent causes.) Simply not enough old people will die for there to be a significant governmental fiscal benefit. Particularly not combined with the economy grinding to a halt.
2. You did it all wrong. You should all have moved in together to a Nuclear Age bunker, and stayed together there. You don't need to stop having ALL human contact. You just have to isolate from the disease. And that can be achieved in a closed community of 2, 5, 10, 20 or 100, as long as it's really closed. Do you think guys at the International Space Station are worried about becoming infected if they still eat together and greet each other with a hand greeting or a kiss? Of course not. The concept behind The Decameron, The Masque of the Red Death, and, to a degree The 120 Days of Sodom, is perfectly valid.
3. Same as closing the schools, I find funny the institutions one after the other which are being closed. For all the boomer jokes, it's funny that the places where millennials buy overpriced coffee imitations are closed; same as the places where millennials go shoot pix and vids in scant clothing for their social site followers next to training devices. I hear that there are places where bathhouses are closed, which is especially strange given that they didn't close them during the AIDS epidemic of the 1970s to the 1990s. It is hard to understand gubmint.