1. Yes it is income.
2. Legally, the purchaser is supposed to pay the taxes and the one renting the unit is supposed to charge the tax and collect it and then turn it over to the government agencies that are entitled to the tax. Whether most who do a rental actually do that is subject to question.
3. Don't know and not sure he is supposed to Issue a 1099 (he is a person you hire and to whom you pay money, a portion of the rental you get, and thus it would seem the need for issuing a 1099 may be the other way around). Also do not know as to tax.