I'll give you the answers that have worked for me, though I wouldn't say you "should" do this. This is where I found the best mix doing similar work.

1 - I would at the very least start with freelancers. There are a lot of great, talented people out there and this is the best way to meet people with whom you may end up having an enduring relationship. I have people all over the world in my freelancer network to whom I outsource portions of jobs.
2 - It depends on how you get paid. If you are bidding project prices then you need to try to match your cash flow planning against how you pay your staff. This take some light financial modeling in most cases. So you don't end up owing someone money when your client isn't paying you for awhile. You can design your terms around this if you are careful about it.
3 - My preference has been to bill the entire project under my name and brand, assuming I have a trusted team. I mark up what they charge me and then make the margin on it to the client. In certain instances I turn over the entire lead to someone in my network and take a kick back or commission on it. Again, it depends.
4 - My way of dealing with this is I control the project management platform through which everyone communicates. That way the "real" names are out there, but it's not all done on email. You will want to have non-solicitation agreements with your team members as part of your deal with them.

I'd be happy to discuss all of this with you in more detail. I've been using variations of this model for all of my consulting for more than a decade.