You should speak to a real accountant obviously.. but I've heard that its entirely possible to be take on personal liability even if you run an LLC. Again, I'm no expert so talk to an accountant, but I've heard something along the lines of LLC's being run by a single member offering no real liability protection. Many accountants seem to recommend S-Corps, but yeah, if you want to have investors you'll need a C-Corp.

As for separating your business operations from your personal ones, that seems like a responsible thing to do.. so definitely do that.. but speak to a real accountant first