1. Investors don't have to have a company to invest, but the success rate of individual or patented projects is really not as high as that of operating (company-owned) projects, unless your projects are particularly good!
2. You can send your project summary to the sponsor in the early stage. If they are interested in your project, they can discuss some details. If you are a personal project or patent, some professional core technologies must be contacted with you.
3. Investors took great risks to invest in you, of course, for profit. Your ways of cooperation can be divided into equity and creditor's rights, depending on how you cooperate!
4. Hehe, your share is too high. They can't get 80% at once. Maybe their interest rate is a little higher than that of banks, but it won't be unreliable!