You need to prep the area under the edging just like you did the patio - something coarse and well-packed for drainage, going to below frost line. If you are going to go to all that trouble, dig it out, and pour a concrete edging and mortar some bricks to it.

Without pictures it is hard to provide advice. I had two plain vanila pconcreate patios and I destryed them and poured a larger patio which I covered in rock and added a pergola. Here is a picture.

You can find more info on calculating wind force here: http://www.vishaypg.com/docs/11874/vpg-07.pdf or here: http://www.wikihow.com/Calculate-Wind-Load I did a quick calculation totally speculating on how your gazebo might look... F = 0.63 * Area * Velocity^2 * DragCoefficient To determine area I assumed 4 rectangular legs at 4" wide and 8ft tall. I assumed a roof that sits on these legs that is 8ft wide and on average 1ft tall (so maybe 1.5ft at peak and 6" on the edges) Then I converted that into meters to get a total area of 1 sq meter for the four legs (4"/12"*.3048*8ft*.3048 * 4 legs) and another 0.74 sq meter for the roof (1*.3048 * 8 *.3048). I used a coefficient of drag of 1.4. I converted your 50mph to 22.35m/s I then calculated the force to be: 764 newtons or 172lbs Other variations: if I change the wind to be 72mph then the force is 352lbs. If I change the area of the roof to increase by 6" and leave the wind at 50mph then the force is 208.6 If I change the size of the gazebo to be 12ft wide (with 1ft roof and 50mph winds) then you get 208.6lbs If I should be using the 2 as the drag coefficient vs 1.4 because of the long/narrow nature of this structure then at the original dimensions and wind the force is 245lbs Also the above is not taking into account the "lift" created on the roof (similar to what makes a sailboat move). So even with a 300lb structure IMHO it will move - it is just a matter of when. Disclaimer: I was doing quick calculations so it is possible I incorrectly converted something from ft to meters, etc. Please check this on your own!

I don't think it could be mudjacked enough to get proper slope, might have to demo and repour. You can save a fair amount by doing the demo yourself, rent a demolition hammer for the day and have at it. Start at the edges and work your way in. I would recommend the 20 lb Makita over any of the heavy 65 lb hammers so you don't wear yourself out. Then your going to need to increase the amount of dirt around the house to get proper grade before a repour. Pavers with a slope away from the house are a better DIY option than concrete pads if hiring out isn't in your budget. I wouldn't recommend doing concrete pads DIY, too much weight and labor, might hurt your back, too hard for one person unless you have a family with multiple men able to mix, pour, level, in a timely fashion and have experience doing so.