If you stick to 4 units (residential)or less the financing is much different. Once you go over 4 the downpayment requirement goes way up plus you run into a debt coverage ratio (DCR) calculation that may cause the downpayment to be higher. You might find owner financing that will allow a small down or maybe 0 down? Beware though, there is probably a reason the seller will take little or no money down.
I'm not sure what you are asking with your triple net question? Generally apartments are not NNN. NNN's are usually commercial (retail included), office or industrial. They are good vehicles if you don't want to "do" anything other than collect a check. You probably can't "create" increased value with a NNN other than factors that are beyond you control. They are very appealing to people that are tired of management of rentals because there is no management or expense with a NNN. Only a check for the rent.
If you would like more info about NNN investments contact me at firstname.lastname@example.org or 626 485-5163
May 13, 2009