Well the answer is a yes and no...
Will registering a company convince the investor you're a "superstar" and will inevitably make him 10-20x return, NO!!!
Will it give them a sense that you are somewhat professional, YES!!
So in the end, it wont make or break a deal, but if you can do it, then go ahead and do it. Just make sure you do your research, i.e. entity type, domicile, foreign registrations, etc.
Yes. There should be an entity legally separate from yourself(s) for the folks to invest in. It can be changed, but it is easy and cheap enough to set up an LLC at least.