Our long side faces south so the other long side faces north. We followed the advice from the ag specialist. This is our first winter with it but it was built last summer. We have thick sod with witch grass and other nasty weeds that grow from roots. I've been building my garden beds using the lasagna method, first putting down a thick layer (about 6 sheets) of wet newspaper. Then layering fresh cut grass, old leaves, etc finally topping with good composted soil. So far haven't had to do much weeding but that will probably change this summer. I had three rows of beds and two paths. The paths were left as grass (we kept running out of time) which my husband cuts with a weed whacker. The sides on our structure roll up. The door is on the west end and wide enough (two doors wide) for the tractor to enter. I didn't plant as many things as I should have since I experimented with how long I could keep a zucchini plant alive and how late I could get a crop of sugar snaps (the heat during the day wasn't good for them). I will probably lay wet newspapers on the paths and cover with fresh cut grass which is what I do for the paths in our outside beds. The composted material can be shoveled on the beds the following year and new paper put down if necessary.

Since I'm two full zones different, I don't feel quite competent to address the questions, but I'll take a crack at them. At least until someone with more relevant experience wades in! We have a 20 x 24 foot hoophouse, intended for use year-round (deep winter slowdowns are expected of course). We have doors at each end and roll-up sides. The layers are plastic with a blower fan to inflate some space and keep the plastic taut. Ventilation We do not have any form of mechanical ventilation and we do fine. Our hoophouse does not get any shade in summer. Air temperatures peaked at a little shy of 120 F last summer--hot, but all the plants--including cool-weather varieties--lived. It is often safer to keep the ventilation means simple, to avoid complications if something goes wrong (power goes out for example). But if there is not someone who will be around to correct things in case you forget to open doors or roll up sides, then a backup system (like an automatic vent) would bring some peace of mind and perhaps save some of your gardening efforts from setback! Securing plastic Ours does have the baseboard and roll-up sides. I wouldn't do without them, especially since it's so easy to make adjustments. In fall and spring, yes, one typically rolls the sides up every morning, and back down by late afternoon--all depending on the temperature in the hoophouse, ambient temp, and cloud cover. It's not a difficult task--only takes about 20 seconds a side (not including walking and checking out what's going on in the garden). But if someone isn't available, then once again some automatic system might help. The sides typically stay up in late spring, summer, and fall. But if a severe storm threatens, or even just a strong winds, then one has to run out there and roll down the sides and shut the doors to keep the structure safer. Insulation Particularly with the winds around here, I wouldn't consider doing anything but two layers with inflation. I don't know what wind conditions you have there--that might be something others will like to know in discussing your project. :) I hope that helped somewhat and didn't muddy the waters. I love hoophouse growing though and am always very happy to talk about them with others. May your project bring you much pleasure and many wonderful veggies!

Are you planning to remove the poly in summer? That would be my plan, just shade cloth in summer. Poly plus shade cloth in winter. The most durable and best for the money shade cloth is woven black polypropylene. I use 30% but also have a very good evaporative cooling system which is a lot more effective cooling in the desert than anything else. You might want 40-50% shade cloth. Mine has lasted 10-40 years of part time use.

You may want to ask this question on the veggie growing forum: http://forums2.gardenweb.com/forums/cornucop/?24140 Winter sowing is a completely different "thing" than you are doing, I don't know if this group would be as helpful to you! Also check out the forum for your growing region/state. I bet there are other hoop house growers there.