1)I think interest only loans are the best thing silced bread. I have been using those on every home I have ever purchased. In my opinion, why pay the banks back when you will be doing that when you sell the home. Your money that you would be paying twords principal could be better allocated to higher interest earings such as the forex market where it is possible to be earning on your money in one month what most earn in a year. I think people are crazy to pay anything over interest only. Invest and if you want to own the home outright pay cash after you have invested.
2)First time buyer makes you open for more loan options. Simple as that. What the biggest factors are debt to income ratio and full doc loan or stated income. Basically the bank needs to see you can afford it.
3)I personally used to think, when I first started investing in real estate, that FSBO would save me a lot of money on realitor fees, but then a good friend of mine (investor in $4mil plus homes only) told me that you need to pay your people well and your properties will sell quicker and for greater amounts. Realitors are an essential part of the equation and pay them well because they will turn more profits for you by reducing the hold time on your properties. Also if you pay your realitor well and they will many times come to you over others with new invetment opportunities they come across them. And trust me when they do come across them they are good.
Sorry for the long reply but I felt like I may be able to help.
p.s. I have included the site where I learned forex trading and currently trade. It is great.