If Darry didn't have Soda and Pony, why would he be a Soc?

I don't think Darry ever would have become a Soc, but had he been able to pursue his studies and played sports, rather than work and take care of the boys, he would have qualified......

Yes he will because the only reason he is not a soc is because of the gang. And it said it in chapter 8 when Ponyboy and Two-Bit were in the hostpital visiting Johnny and Dally Two-Bit brought it up.

Yes

Yes, Darry would be a soc if he doesn't has Pony and Johnny because Darry is very clever and the only way he keeps himself from really becoming a soc is his struggle with money and his care for his brothers.