Food additives -- 100 found inside hampers (9)

'hampers' is the definition.
Although both the answer and definition are verbs in their -s form, I don't see how they can define each other.

'food additives 100 found inside' is the wordplay.
'food' becomes 'e' (E is an example).
'additives' becomes 'numbers' (I can't explain this - if you can you should believe this answer much more).
'n00' becomes 'c' ('C' can be a synonym of 'n00').
'found inside' means one lot of letters goes inside another.
'numbers' placed around 'c' is 'ncumbers'.
'e'+'ncumbers'='ENCUMBERS'

Can you help me to learn more?