Friendly contact is to unlikely it is ridiculous for one very big reason, the notion of alien concepts, confusion, and fear will drive both sides to a dubious stances AT best.

Their attributes would depend on many elements of their origination, clearly if they come from a planet in which there is more gravity, and drag than on our planet they would naturally be stronger and move quicker than they themselves normally would be -- Does that mean they will be stronger? Depends on physiology -- I don't remember the Anime but there was one about a Mar Colony, and for some reason the humans on Mars due to the gravitational field were born, and developed to the point of being dramatically weaker, and more frail than Earth bore humans.

Or you could run with the notion from the movie "K-Pax" that the Humanoid Bi-pedal form is the most efficient, i don't think it is, as when you evaluate many things about our make up it's easy to see our flaws just comparing them to animal, and insect species on our planet alone, examples include the placement of our eyes, the size of eyes, single lens, low amount light sensory cells, muscle size to power ratio, no redundant organ systems, we heavily depend on our diets for too much to function, poor ATP synthesis -- thin epidermis/dermis/subcutaneous, lack of natural defense to avoid penetration, and perforation of skin, all in all the only real advantage to the humanistic build is that we are built for intelligence, everything from the size of our digestive tract down to the shape of our neck are all created so that we can developed big brains, that however has created the biggest flaw to the human design, the head - Our heads are fragile, with but the most minor contraqueing force rendering death, and furthermore a neck that can easily be cut clean through.

There is a great documentary series out called Evolve, they look at all the different aspects that make up creatures, and deduce what affects they have in the direction of adaption, and what it means in the big picture, it's interesting to see how the simple things such as having the ability to chew your meal, and digest it later can mean in the long run, versus lets say a cow, that grazes, digests, THAN chews their food, and sends the food to another chamber of their stomach to finish digestion, this in  turn makes the process very long,  drawn out, and requiring the animal to spend most of it's awake time eating, or chewing, to sustain it's size, thus not allowing for too much more in their lives other than eating, interesting stuff.

Btw if your thinking aliens, think Enders Game and series

Btw I am Peter muwahaha

They would have the same problems with space travel like we do.  Interstellar hazards, micro-meteorites, bone loss, elevated white blood cell count (or their version of it), radiation, solar flares.   And like pioneers they would have to navigate and blaze a trail across the western sky's, WAGON'S WESSSSSSSST!!!

They have to get here first.  And they'd have to find us.  Let's say two individual species, us and them, forming within the milkyway galaxy....your talking billions of stars, trillions of planets, several trillion moons.

They have to find us first.  Our galaxy is what? 70,000-90,000 light years across?  Our strongest radio signals to leave our atmoshpere was back in the late 1930's, early 1940's.  And those signals have travelled roughly 70 years in interstellar space, on only a few hundred frequancies, with tens of thousands of frequancies to listen to, mangled with interstellar radio noise...

It's not looking good or pretty for two intelligent species to find each other.

With all our flaws the fact we survived to become as dominate as we are with our intelligence is simply a fluke. Neanderthals could have easily been wiped out by any predator of the time.

Hell why worry about aliens from space when we can't even deal with the aliens to our country here on earth Imperial?