[RPG] Do sorcery points have any value at level 2

Casting a Spell at a Higher Level
When a spellcaster casts a spell using a slot that is of a higher level than the spell, the spell assumes the higher level for that casting. For instance, if Umara casts magic missile using one of her 2nd-level slots, that magic missile is 2nd level. Effectively, the spell expands to fill the slot it is put into. Some spells, such as magic missile and cure wounds, have more powerful effects when cast at a higher level, as detailed in a spell’s description.
—Player's D&D Basic Rules, page 78

Since the slot is 3rd level, the spell is 3rd level. Since the spell is 3rd level, 3 points are needed.

Note that, for many spells, a higher level slot does more damage, as well. Ray of sickness does two extra dice of damage as a 3rd level as opposed to 1st...

Yes.

The sorcerer's Flexible Casting class feature allows the sorcerer to expend 6 points to create a level 4 spell slot and the sorcerer can use that slot to cast a lower-level spell that he knows.

There is no restriction on creating or using spell slots of a higher level -- the only restriction is that you don't get those slots back on a long rest. On the other hand, if you have the slots, you can use them, even if your current class level doesn't explicitly grant them. Also keep in mind that slots created with sorcery points always disappear after a long rest.

This is further reinforced by the rules for multiclassed spellcasters, quoted below, which state that if you have slots higher than a level you can cast, you can use them for your lower-level spells.

If you have more than one spellcasting class, this table might give you spell slots of a level that is
higher than the spells you know or can prepare. You can use those slots, but only to cast your lower-level spells.