Are there investment corporations that look for persons who have new business ideas?

Do investment firms look for businesses or for people with ideas for a new type of business that they could finance?

Not really. Venture capitalists want way more than an idea. At the very least, you should have a professional management team (not necessarily committed to the company full-time at present, but ready for such commitment should venture capital funding materialize), a prototype of your product/service and/or the results of a concept test, a patentability opinion from an experienced patent attorney (if applicable), and a business plan that can convincingly show how you and your team can create a multi-million dollar business in three to seven years.

Note also that most venture capitalists prefer to invest in large transactions (some start at $5 million, some even at $20 million). The implications are twofold. First, you should have a management team that has experience managing multi-million dollar projects. Second, you should be aiming to create a company that would be valued in tens or hundreds millions of dollars within a few years.

Yes.

First step is a good, well written business plan.

If you don't have one, you're not ready.

I would want to know what kind of a return I could make on my investment and in how long and with what risks.

I prefer to see three scenarios, a pessimistic, optimistic and middle of the road.

Yes. They're usually called venture capital firms.

Generally Venture Capitialists will fund existing small businesses, but at a cost. Existing corporations rarely hear ideas from outsiders.
Good Luck with your idea!