Many professional composers use samples. I could not imagine composing music without samples. Sorry, I completely disagree with you. I don't know if you listen to rap or not - but its music is mostly made of samples, completely. Samples are also important part of electronica music. Moby (if you know him) composed his early tracks using samples too. Many trance, drum'n'bass, chillout (and other electronica genres) tracks are composed using samples. I can say that playing shitty guitar is fake and gay - newbie way as well. Will that change your opinion? I think not. Music is music. Music is everywhere. Samples, original instruments, one-shots, whatever. The important part is how it sounds, not how it was composed. My friend composes his music using samples. I don't really like his music, but some of his tracks are just amazing.
Yep, sample for C3 note of strings. It's nothing bad.
Not full loops, but only notes samples. Things like Akai MPC or professional synthesisers/keyboard (Yamaha TYROS 3 and so on) also use samples cause sounds generated by sound cards are shit. If you don't know how it sounds, try generating a raw saw sound.
Strange... I had to listen to it twice to like it. The first time I couldn't really hear the melody. You should lower the volume of the background guitar or something...