Word classes and more

I got a few task which i don´t quite understand :
1) Word Classes
Nouns are considered lexical words; determinal grammatical give 3 criteria that support that distinction.

Is it like sementic,morphosyntactic and syntactic criterion?
-Sementic: nouns refer to entities such as objects or individuals.
etc.

2) Name one morphological 1 syntactic and 1 sementic criterion that each contributes to the definition of the word class verb.
- Inflect for the morphosyntactic categories tense, number, person - > 3rd person singular
Semantic - > denotes action
syntactic i dunno

Heads and modifier . Give an example for a noun phrase with 2 different kinds of modifier?
- ?

4) give an example that in english there is no fixed order for heads and modifier within phrases!
- ?

5)Susan gave her dog biscuits-> why is this ambigious (Constituent structure)