I fitted the 5Exi hood recently and can answer most of you questions.
1) they lay flat not sure how that would fit any other way to be right.
2) once the zipper is undone its all accessible from inside
3) with the front tucked under the screen surround and pulled taught I angled mine back as far as I could for a better streamlined look from the side.
4) TANEX buttons on the side and turrets at the rear corners where you need the strength, buttons over the top at the back. In front of the rear engine grill I put turrets so that were easier to remove at full stretch without ripping at the fabric.
I have a a number of picture of my interpretation of the fit but its easier if you PM me your email and I can send them direct.
I have a couple hosted and will post them up but I have many more....
Do the fitments on a hot sunny day in the sun and the fabric is easier to stretch and manipulate. It will give a better fit and look if its good and taught.
I used chromed brass screws and SS nuts to avoid rust, you can pop rivet them in place but screws are just as easy, I did not need to fit back nuts on all the side buttons as the GRP is strong enough to be threaded (and my arms were not that long anyway). The turrets are all threaded and back nutted.
On the screen cover, over the front, make sure the backs of the two buttons fastener, whatever you use, are either not over the edge of the screen or are well protected from pressing on the glass underneath. It is reported that over zealous pressing of the screen buttons and the 'click' into place has cracked screens and that's £400 you could do without spending.
Hope that helps