***** NOT A TEACHER *****
Wannaknow,
(1) I have done some googling and wish to report my findings:
(a) "Bunchful" is a word used by some native speakers, but it does not seem to
be accepted as standard English, so it might be a good idea if you do not use it.
Here are some examples that I found:
(i) He ate carrots by the bunchful.
(ii) Only one company is fully issuing a bunchful of titles.
(iii) Gave Dylan a bunchful of wild flowers.
(iv) These were quite a bunchful of fates and or coincidences.
(v) A whole bunchful of prayers.
(b) Google "books" had only three pages of results. That indicates that most native writers avoid this word.
(2) Thus, you might consider:
A
whole bunch of surprises are waiting for the winner of the contest.
A
lot of surprises are waiting for the winner of the contest.
Many surprises are waiting for the winner of the contest.
A great deal of surprises are waiting for the winner of the contest.