Freelancers: content writing, transcription, and a variety of other work

I am a full time freelancer who has suddenly found myself swamped with more work than I can handle. I have several clients who have ongoing work for me, and I do not want to turn any work down. What I would like to do instead of turning work away because I simply can't keep up with it, is start offering projects to a few, high quality freelancers who are either just getting started and need the work to get by while they build up their own client base, or who are working small freelance jobs on the side of a full time career for extra income. Most of the projects that I receive include copywriting for web site content or newsletters, and involve the use of keywords positioned in specific locations throughout the article(s), transcription work- where I receive mp3 audio files and type the interviews or other audio word for word for the client, and sometimes web related work including site design, promotion and marketing services, and link building. I will definitely need to see samples of your work prior to asking you to take on one of my projects- because the projects are coming from *my* clients, and they expect the high quality services that I provide them- so if I branch out some of the projects and distribute them among other freelancers as I get overloaded, I need to feel fully confident that the work that freelancer is going to provide will be ON TIME, TOP QUALITY, and free from any grammar or spelling errors, completely and 100% the freelancers own work (no plagiarism), and basically- I receive repeat work from all of my clients becuase they are so happy with the work I provide- and I do not want clients to stop giving work if I decide to branch out and share my projects with other freelancers! So I realize this is a lot to take in, but to sum it all up- I'm looking for a few high quality, dependable service providers who want to receive a few projects here and there, sort of an "overflow" of the work I receive regularly. If you would provide a bid that indicates what you would charge for content writing of a document of about 300-400 words, making use of keywords, that will help me get an idea of your rates. We'll discuss rates on each project however as it comes up and make a join decision that is fair for all involved. In your comments for your bid, include where I can find samples of work or more information about the services you provide. Thank you for your time.