At higher character levels (17 IIRC) you start getting +2 stat boosts, rather than +1.

Metal scraps can upgrade cloth and leather armour (plate or scale scraps upgrade scale armour).

Crafting: EE guide and searchable/filterable list

If you are playing D:OS Classic (where 1 talent point could get you 10 ability points; that was cut to 1 in the EE), there is a Crafting Recipes & Guide topic, and pdf download.