1 - Well, sometimes the texture and taste are sliiiiightly off but it's usually pretty close and, I think we'd both agree, a damn sight better than unnecessarily killing animals.
2 - I don't know if you're aware of what happens in egg hatcheries, when the fertilized eggs hatch. Basically, the females are kept as layer hens and the males are ground up alive or gassed in a bag. They're treated by the industry as just a "waste product", just because they won't produce eggs.
The females are kept, have their beaks cut off with a hot blade, have their wings clipped and are killed for cheap meat, after a life of producing an unnatural amount of eggs, which has a very taxing effect on their bodies. They are killed when they can no longer produce eggs.
Does the unnecessary killing of innocents justify us consuming eggs, when we have alternatives to get taste and nutrients from?
In the dairy industry, male calves are shot in the head or sent away for veal, on live export trucks, just because they'll never produce milk. Again, the industry treats them simply as a "waste product".
Does this justify us killing these babies, when we have alternatives to get taste and nutrients from?
3 - Yes, plants are alive but they are not sentient. In order for a being to be sentient, they have to have a brain and a central nervous system, which we would find if we cut into an animal's body. Animals, like humans, also react to situations and attempt to get away, out of fear for their life, when we threaten them with guns or knives. When we cut up plants, do we find any of these and do plants attempt to get away? Plants are static and can't run away. Wouldn't it therefore be cruel if plants did feel pain?
Finally, many more plants are "killed" in the production of animal products than in the production of plant foods, as it takes 16kg of grain to feed one farmed animal.