wnt - steel siding tutorial

Hi all. I'm new here but there is obviously a wealth of information kicking around with you folks. I hope someone can steer me in the right direction.
I had a fellow begin this job and not finish it. I found some glaring errors in venting and with the siding installation that I had to put a stop to.
The siding is my main concern just now. I went looking for a tutorial to get me up to speed with some of the general practises but found nothing. Any links to help bring me up to speed would be appreciated.
http://ca.geocities.com/itschaotic/home/addition/index.html This URL shows where we left off at freeze up. Hopefully this old building will all look like one structure this summer some time. I have a new, tiny (200 sq/ft) floor heated clean shop (lathe, mill/drill) inside what's left of the old building you can see attached to the new construction.
There is no venting along the ridge of the roof and no end venting so I can't finish much inside until the venting is looked after.
I intend to change the ridge cap to a venting one. I'll have to cut the roofing steel away from the peak and cut away the strapping for a few inches to let the air up through the new ridge cap.
Question #1 - Should I buy a diamond blade for my circular saw or invest in some electric or air nippers?
The door isn't hung well, the j-channel around the windows is set to drain inside, at least one of the sheets on the walls is buckled around a window, outdoor electrical outlets are hack jobs needing silicon. The roof is also missing the foam inserts top and bottom.
Question #2 - what's the best type of sealing foam to put under the steel on the roof sheets top and bottom? Are all those foam seals created equally? Do you guys have a preference?
This is steel sheeting. I can't live with it like this so I'm going to have to learn something about steel siding installation.
Inside the electrical is close to being finished. I'm almost free to get back at this job and need to learn a few good habits with steel siding installation first.
Question #3 - How should the j-channel be installed around a window? Or is this just common sense and silicon to get it right?
Question #4 - should there be foam inserts on the top and bottom of the wall sheets as well?
Hope to hear from you all soon... well maybe not all. Cheers! Ian.

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