Hi,
I am a structural drafter in my real life, I have designed similar building details before and am familiar with the most common construction methods, in Australia anyway, I would be happy to have a go at this for you and, with your input, we can work through it until you are satisfied. I could start in the next 24 hours. Please feel free to contact me if you would like any more information, also feel free to browse my portfolio for a couple of examples of my work.
Cheers,
Brett
edit. I am a little unsure of the need for illustrating diagrams, the structural details would show the builder how it is to be built, maintenance could be covered by a few notes regarding rust prevention.
Fabrication drawings would normally be done by a professional steel detailer, usually the steel company will have a drafter that does this.
The rest I can detail no problems, with some information from you of course, I would send you the drawings for your comments as I work through them.
Cheers.