I’m not sure what you mean by powering half of your layout but, if your are blowing the fuse (circuit breaker), you are over the limit.
You can use the 4045 to power the lights. It is rated at 45 watts so you have somewhere between 35-40 watts, or around 2.5 amps, to work with. Definitely use a fuse of no more than 2.5 amps. A small incandescent lamp will draw about 1/5 of an amp at 14 volts so you could connect about 12 bulbs. Many of these buildings have more than 1 bulb in them, so you need to count bulbs, not buildings.
So many people recommend LED’s because the power requirements are less than half of that for incandescent lighting.
