Yes they can. But dinner suits shouldn't have stripes, so maybe get a nicer one. :)
Impossible to really tell the quality from the picture, and can't tell the size either. But assuming the leather is real, even if it's not the best and a small satchel as suggested above, $100 seems like a good price for anything leather and new-looking.
3-3.5 is normal really. Pretty safe range for any body shape. Thinner always looks more casual, and to me a bit Justin Bieber; too wide looks like pimp-wear. So stay where you are and you'll be fine. The exception is knitted ties, that are normally rather thinner, but you're on the right track already, don't get hung up on it.
You're a slim man so the first one didn't look "skinny". And it would have been more helpful to see pics with your jacket on. All three are fine, and suitably conservative for any use.