1. Half-elf or variant human would be the strongest races mechanically. With standard array you I'd probably lean toward half-elf in this case, since that lets you start with 16 in CHA, DEX, and CON, and an extra skill (darkvision is nice too). If you go human I'd get 16 CHA and 14 DEX and CON, and probably take Lucky or Alert as your feat. Maybe unless there's nobody who can cast rituals, in which case you might want to do ritual caster (Wizard) for some utility (start with Find Familiar and either Detect Magic or Comprehend Languages).
2. Whatever suits your idea of who the character is. Sorcerer can already get all the social skills, so you don't have to pick something that grants those.
3. Definitely start with 16 CHA as your highest priority, followed by DEX, followed by CON. The bottom three you can arrange however, but I'd put the 12 in WIS, for perception and a more common save.
4. At low levels you might consider skipping the blasting and taking spells like Sleep and Web, and transition to more full-time blasting once you can get fireball (be sure to swap out Sleep for something else around level 3 or so if you go this route). If you want just a little CC, Web is strong on its own merits, but also has the nice synergy with fire spells that you can torch it if you want. I'd probably do something like:
Cantrips (1st): Firebolt, Minor Illusion, Friends, Prestidigitation
Level 1: +Sleep, +Shield
Level 2: +Disguise Self
Level 3: +Web, -Sleep, +Shatter
Level 4: +Control Flames, +Mirror Image or Misty Step
Level 5: +Fireball, -Shatter, +Hypnotic Pattern
Level 6: +Thunder Step
Level 7: +Polymorph
Level 8: +Wall of Fire
Level 9: +Animate Objects
Level 10: +Shocking Grasp, -Polymorph, +Hold Monster (if taking Heightened)
Level 11: +Chain Lightning, -Polymorph, +Mass Suggestion (if taking Subtle)
Level 12: ---
taking Empowered Spell and ... probably Quicken at 3rd, then Subtle or Heighten at 10th. But I wouldn't use Quicken to add a cantrip to your turn; save it for situations when you might really need to dash or dodge or something like that. You could even consider taking something like Eyebite or Sunbeam at high levels, and leveraging Quicken to keep casting other spells even as you use your action to keep triggering those. Subtle is lovely for many reasons; I'd take it at lower levels if I wanted to use spells in social situations, but this is primarily a combat caster, so it will be more useful for you at higher levels once you start facing more casters with counterspell, etc.
5. For feats, I'd probably get CHA to 18 at 4th then take elemental adept (fire) at 8th (resistance isn't super common at lower levels, unless you're playing Avernus, but if you're playing Avernus don't be a draconic sorcerer), but there's a strong case for Alert too, to help get your AoEs off before your allies are mixed in. At 12th probably just finish maxing CHA.
6. Probably use a light crossbow primarily until level 5, at which point switch to fire bolt. (But have fire bolt earlier in case you run up against something with resistance to non-magical piercing.) Pick up a couple daggers in case you get caught in melee. You have no need for armor or shields. You might want to get a healer's kit, since with Quicken Spell you can cast a spell and go stabilize somebody if needed. Might not ever come up unless healing is scarce in your party, but they're cheap and it can't hurt.
