Its always wise to buy your own home when you can.
The first thing I would advise you to do is work out the price of the apartment per unit area i.e price per square meter. This would make is easier for you to compare 2 different projects in terms of size, finishes and finally location. Size is a matter of perception to most novice buyers, and something developers take advantage of very often, you may end up paying significantly more for a 2 bedroom apartment per square meter.
Finishes should also be an important consideration. A house is not something you buy everyday and it is a significant investment, therefore you must ensure that you are getting your money's worth. look to see if the tiles are of 2nd grade, what kind of plumbing fittings have been used. Do the kitchen cabinets look like they'll fall any minute...alot of stuff you could check.
Also look out and see how the common areas have been done, look at the thickness of the paving blocks, if they are the thin light duty ones in an apartment project, then something is not right.
Ask about the management structure of the project once the ownership is transferred to buyers. What common amenities will be provided and how will they be maintained. What will be the monthly service charge?
Location is also extremely important in both current and future outlook. Find out if there is a likelihood of a new road/bypass coming up next to the project that will alleviate jams in the future. If you are to raise a family there are the required social amenities nearby e'g school, church. If you plan to rent in the future then it would be wise to find out the rental potentials of the area and the estimated rental yields against your investment.
Look at the security in the area, nearby amenities and the surrounding projects as they will give you good idea of the kind of people you will be living next to.
I think you should reconsider your decision on mortgages, indeed the 15% is high but you will benefit from increased gains in property appreciation. By this i don't mean for you to borrow as much as you can, borrow within your comfort zone and take advantage of leveraging.
Reading your post these are the few things I can say from the top of my head, if you have any specifics do ask.
Before you can be be old and wise, you must first be young and stupid.