To answer a few of the questions I use 3 snaps at the top which are attached to front side of the hatch pull. The sides are reinforced to give it some structure. At the bottom, I have sewn in a 3/8" galvanized rod with the ends protected from chaff with topgun sleaves, this I have found holds the bottom on the outside ot the compainion way track. For the window that is attached with Velcro. As for the sewing machine, I took the plunge and purchased the Sailrite LSZ-1 at the last Annapolis Sailboat Show. If you check Harbor Frt's web site you will also find an industrial unit that they handle but, I have not seen any reviews on the unit. Another reason that I purchased the LSZ-1 was that I was recanvasing this year so it came in handy for making several of the pieces. As for thead I have been using the UVR Polyester V-92 thread and perhaps sometime I will try the Tenara thread.
Hope this info helps
Bob