When purchasing weapons a player should be given a choice to either equip, store or load the items into available cargo space.

Only if there is an option to tell the options to stfu so I can leave it how it is now for quickly setting up ships. ;)

+1 (Buy&Equip) (Buy&Load) (Buy&Store)

(Buy&Load) will fill up cargo capacity then place remaing items, if any, in station storage, as (buy)commodities does.