Hi Nicki
I would ask the manufacturers for photos of the inside of the coop so you can see the internal arrangements - roosting bars nest boxes etc. Otherwise it look quite well built - though the pop hole is not suitable for an auto opener if you decided to get on in the future.
A 5' fence *may* keep hens in, but bantams tend to be good fliers due to their lower body mass in comparison to wing span. Certainly a 5' fence wouldn't keep a fox out, so you would have to think about increasing the height if the fence and bending the last foot or so out at an angle so the fox cant climb all the way to the top.
Thirdly the run space you are suggesting (2m²) is insufficient for even 2 bantams. DEFRA states that birds should have at least 1m² each; however if they are going to be in a fixed runn then you really ned to give them as much space as possibel, 2 or 3m² each is not unreasonable. And this is separate to the space you need for feeders and drinkers, and other "enrichments" (i.e. dust bath, perches, space to hang up a cabbage etc).
If you can make a bigger space from them (and for 4 bantams I would recommend no less than 8m² in a fixed run) then shade could be provided with a tarp, or "enviromesh"/debris netting if it didn't have to be water proof, or Onduline or coroline would be a more permanent solution.
If you have "launching pads" then certainly your chickens could escape into the forest. I used to regularly have 9 birds almost 20 feet up my apple tree until I removed the "stepping stones."
In answer to your questions "Also will they ruin the garden?" the short answer is YES! They will love removing amy mulch you have on borders, they will dig up your bedding plants and bulbs. They will scratch up your lawn and poo all over your terrace/porch. generally if your hans have access to the garden a lot of the time, in winter it will become a mud pit - I speak from experience. I now have a large pen which is only for the chickens, that way I have my nice "front" garden, and the chooks have their own space at the back, which currently looks like a moonscape, but they are happy in theri space lol.
Well done for thinking about everything first, though. It is a very sensible decision. I can heartily recommend the Haynes Chicken Manual as a great place to start (I have no affiliation with the publication - I just rate it as an excellent book for beginners)