I'm not a financial planner or financial services professional of any kind, so take anything I say with a grain of salt.
1) should I stop saving?
No. negative interest rates won't go that negative. Even if your bank is earning -1% interest, it still makes sense to be saving.
2) Should I put my savings elsewhere?
Probably. ETFs or index funds with wide stock market exposure are a good idea (good examples are SPY, VOO, VO, VFINX... and many others). You make money by buying stocks when the market is low and selling when the market is high. Long term, it will probably go up as it always has. That said, it's very hard to time the market, so the best strategy is to put your money in over time. One good way to do this is to take a set amount of money from each paycheck and invest it every pay period, regardless of what the market is at. If you have a bunch of money sitting in savings right now, maybe divide it into 52 parts (or 104 or 156 or even 208 depending on your risk tolerance and/or thoughts on how long this market decline will last) and invest that amount each week.
3) Should I take out loans to buy up assets?
Probably not. No one is gonna give you an unsecured loan at a good enough rate that will make this worthwhile. And a secured loan will be against something like a house, which you probably don't want to risk losing. This is almost never a good idea.
One big exception might be buying a home. When the dust settles, the real estate market might take a big hit in which case taking out a loan (i.e. a mortgage) to buy a home might be a good idea.
4) Should I build businesses and raise venture capital for them?
Depends on the business. Venture capital money is going to tighten up a lot. People just aren't going to be throwing around money during a recession in the way that they did 6 months ago. But if you can stomach it, this is probably as good a time as ever to build a business that can get to profitability quickly. The only caveat is that it might be a risky time to quit a job with a stable income. Typically, it's easy to take for granted that if your business fails you can just get a job. Right now, that seems less certain.