Yes, another fork could be installed on the bike, although it might not be cost prohibitive. Perhaps if one finds a good deal on a closeout fork, but remember they are generally a very big percentage of the cost of a bike. Either way, the Giant is a great bike to get started on!

As for full suspension bikes, I suppose changing the frame could potentially happen although again, VERY VERY costly! This is NOT something that I would recommend.. it simply would be less expensive to buy another bike.

Have fun on your new bike