I used this knife while camping and after using it to cut up some meat the blade looks blue now. Does anyone know why?

Did you by chance heat the blade to sterilize it? If you applied high temperature or flame to the blade it could have created a heat induced patina. Otherwise there could have been acidic reaction from different juices or marinades. I recommend using a good metal cleaning agent like “Bar Keepers Friend” or you could go the route of using something simple like WD-40 or Rem Oil to see if the coloring returns to normal. If not, I don’t think that the performance of the knife will be affected in any way. This is a truly great quality knife that will last a lifetime with proper care and use.

is this a full tang knife?

3/4 length tang with about 3/4 width as well. To give the handle something to grip, chunks of metal are stamped out - “U” like, one up then one down. This prevents the blade from either pulling out or getting shoved into the handle, the alternating up and down notches give the “melted on” handle gripping surface. In real life use, all the Mora’s are sturdy even the lighter ones like the Basic. However if you are batoning to split firewood, use common sense - the Robust, Garberg, and Heavy Duty models are better choices for more serious bushcraft with batoning harder and thicker woods. The Basic in particular has broken inside its handle in two online videos, in both videos, failure occurred when the pronounced Basic finger guard was allowed to rest on a flat surface so the hand became de facto immobile, then the tip of the knife on the other side of the chunk of wood was hammered down with a stick; that “rocked” the blade on the finger guard as pivot and snapped it inside at one of the notches. As a rule of thumb don’t baton with less than a 3.0mm blade thickness, and in an emergency with thinner blades, baton with moderate force and don’t resist the handle from rocking up in your hand - don’t push down hard on the handle at the same time you baton the tip. Be patient and baton the tip first then rock the handle down with the least force it takes. tl;dr - don’t baton if you can avoid it, and select thicker blades if you must. Also carry a Basic as backup, just 4 ounces with sheath, and gram weenies can masking tape the edge and carefully carry it without sheath for use only in a true emergency.

will the knife stay in the sheath if mounted upside down?

Hi Smokin, Yes, but with a qualification. It fits with pressure- not a strap or lock. It is possible when taking it in and out to not "seat" it all the way. Then it can flop out. I strap them to the outside of my pack and have never lost one or had one fall out. I like the fit of these molded handle models better than the Mora's with smooth rounded handles and tube-like sheaths. A mod could prevent it falling out. I would not recommend depending on the sheath fit and carry it upside down or bungee with it!