Having H1 and entering monthly will raise the question on why to have H1 when B1 serves the purpose of requirements gathering(as you said meetings). So one or the other officers will ask.
And Yes they have every right to ask the purpose of visit and the relevancy of using correct visa for correct purpose.
USCIS , consular officer and CBP officer have equal rights to admit and review the cases. CBP has the same right as the consular who rejects and asks uscis to review the eligibility of the candidate seeking a particular visa class.
CBP denies entry of a candidate if he feels wrong visa class is used(which is abuse of visa). Do you think that they will let you in just like that just because candidate has visa and uscis approval? Its not the case. Saying the purpose and having the documents alone is not enough - the correct visa class for that purpose should be used.
Its perfectly legal to live in Canada and work in US. You don't need to hide anything.. After traveling between US and Canada almost every other week.. Normally the conversation with US CBP is like:
"Purpose of visit" : I work in US at [insert company]
"Why were you in Canada": I live in Canada. I am a permanent resident here.
That's it.
Fortunately, my company is a famous one (one where you stream movies, tv series online) and normally there is a small banter around some content which they didnt like.
On Canadian Side: its even faster.
"How long you were in US": Usually, 3-4 days
"Why were you in US": I work there.
And that's it.
So, I am not sure what's wrong in not being forthright with CBP.