1. 8.5% is definitely below your tax rate if you were paying the federal government taxes, so if the money you were saving is worth the hassle, then go for it. I would do it, if I were rich....
2. When I went to invest in mutual funds, the lady did say something about the interest that would be incurred on borrowing to invest in "non registered" funds would be tax deductible, but I'm not sure about RRSPs. I remember the borrowing rate was quite high - probably more than 8.5% and I'm not that keen of an investor that I would be comfortable making a return greater than 8.5%.
3. Everybody is going to give you a different answer. It depends on the risk that you're comfortable with.
Has an IQ of 138, but can't figure out basic algebra.