A good synonym for "forewarn" would be "admonish",because they both mean warn in advance.
a synanym for approxiamtly is exactly, or even 100%
A good synonym for "incentive" is "motive".
blindsided
A good synonym for "rushed" would be "hurried".
A synonym for "boarding school" is "academy".
synonyms for "remuneration" are "payment", "reimbursement", or "compensation".
I believe a synonym for "share-cropping" is "farming" or even "agriculture".
A synonym for "hominid(s)" is "human-like"
Keen is a synonym of "eager"
ambush and blindside are two possibilities.
There are 2 syllables. Fore-warn.
The homophone for 'four' is 'fore' as in 'forehead' or 'forewarn'.