Do I need a reentry permit?

I got my green card earlier this year. I recently accepted an offer to
teach at a university in Canada from January. The initial appointment
is for three years, and since it is my intention not to be in Canada
longer than 3 years (most likely less), I am thinking of applying for a
reentry permit as I would like to eventually come back to the U.S. I
understand that a reentry permit is no guarantee that I will be allowed
back, although it diminishes the chances of such a denial. While in
Canada I will be working on a temporary work permit (as opposed to
seeking permanent residence) and will be returning to the U.S. to visit
my family and friends every few months. I will also maintain my U.S
driving license and car registration (the province I am moving to is
okay with this so long as my stay is temporary). I will continue to pay
U.S. taxes.

Given this scenario, I would like to know the following

1) If I enter the U.S., say every month, do I really need a re-entry
permit?
2) If I do get the re-entry permit and use it would I be "abusing"
the purpose of the permit, which if I understand correctly, is meant
for those people who will be abroad for more than a year.
3) As with many Canadian cities, the city I will be working in is very
close to the border. Is living in the U.S. and working in Canada an
option? Would this raise abandonment issues? Since crossing the border
every weekday is very impractical, if I maintained two residences (one
in each country and across the border), so that I am in Canada during
the week and come back to the U.S. for the weekend. Could this be
considered abandonment?
4) Finally, I know of court cases where people have been found to have
abandoned their green card due to long absences (e.g. Singh v Reno,
Aleem v Perryman, Moin v Ashcroft ). In all these cases the green card
holder tried to enter the U.S. after a long absence and without a valid
reentry permit. Can anybody cite examples (especially documented
examples) where individuals were considered to have abandoned their
green card in spite of having a valid re-entry permit.

I appreciate your replies, which I think will benefit not just me but
others in similar situations

M.

1) If I enter the U.S., say every month, do I really need a re-entry
permit?

Probably not

2) If I do get the re-entry permit and use it would I be "abusing"
the purpose of the permit, which if I understand correctly, is meant
for those people who will be abroad for more than a year.[/quote]

No

3) As with many Canadian cities, the city I will be working in is very
close to the border. Is living in the U.S. and working in Canada an
option? Would this raise abandonment issues? Since crossing the border
every weekday is very impractical, if I maintained two residences (one
in each country and across the border), so that I am in Canada during
the week and come back to the U.S. for the weekend. Could this be
considered abandonment?[/quote]

That's definitly a good option

4) Finally, I know of court cases where people have been found to have
abandoned their green card due to long absences (e.g. Singh v Reno,
Aleem v Perryman, Moin v Ashcroft ). In all these cases the green card
holder tried to enter the U.S. after a long absence and without a valid
reentry permit. Can anybody cite examples (especially documented
examples) where individuals were considered to have abandoned their
green card in spite of having a valid re-entry permit.[/quote]

Don't know. I'm not a lawyer


I appreciate your replies, which I think will benefit not just me but
others in similar situations

M.