What's the size of the large fully assembled (width & length) including the legs? In picture, legs seem to extend further out than just fabric area.

The bed completed measures 42" x 25" with each of the legs coming out 4". My dogs REALLY love this bed, and though I was skeptical about getting it at first, but I am so happy I took the chance because neither dog wants to lay on anything else since it got here, hence I now have to purchase another one for my small dog. Oh, and a note, it is so light that even fully assembled it was easy for me to carry outside for the dogs to lay on while in the yard.

Can the cover withstand chewing?

So, Maggie is my 2 year old Rottie. She weighs about 90-95lbs. She is a power chewer but doesn't chew her bed. The angles of everything don't make it easy for her to chew, so no issues there. She does scratch vigorously on her cover and has for a year now and it has not damaged the cover. HOWEVER, she gets excited and jumps on it and slides it into the wall. She has just started to bend the corner supports. So I am replacing it with a new one. At $28/$30 bucks, it cant be beat! She loves her Coolaroo. Oh and it helps keep her off of her humans' furniture. I'm thinking because it is elevated. We just love this bed.

Is this good for a 10 week old chocolate lab puppy? Her padded bed has already been chewed up.

WE raise labs and they will chew these beds up. After about a year old you might get by without them tearing it up. We have also put a blanket over the bed and that seems to delay them from destroying the bed. You could also keep the bed away from your dog during the day (when they tend to get bored and eat the bed) and only let the pup use it thru the night. Our labs are now all over 1 year old and all 5 love these beds.

Is this type of bed good for older dogs with some arthritis? Has anyone whose dog has arthritis tried this and a memory foam bed?

I bought both this and a memory foam bed for my 12 year old Maine Coon cat since he has always loved laying in pet beds, but has been doing it less and I could tell he wasn't as comfortable as he use to be in his old one. He's 25 pounds and fits on the small cot perfectly, his old man bones seem to do well on this, since he either laying on this or his memory foam bed. Here is the memory foam bed I bought for him: http://www.amazon.com/gp/product/B009SPZ5YE?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00