24v astable circuit
To me_guitarist: note that there is a mistake in the schema you posted: the resistor in series with the LED in Collector circuit of transistor T1 must be 470 ohm, not 470k.
To connect the bulb 24V-3W, you should know that resistance of this bulb when lighting is 24x24/3 = 190 ohm, when it is not lit, the resistance is about 10 times smaller, e.g. about 19 ohm, so the collector current of the transistor may go up to 24V/19ohm = 1.3A - need to pay attentions when choosing transistors.
The lamps will be connected in collector circuits of transistors, replacing the resistors. However, it is not simple replace the resistors wiht the lamps, you have to change values of other components, as well as adjust for frequency and duty cycle of the wave.
For more details in circuit and calculation, you should refer to the book "Theory and Design of Electronic Circuits" by Eugenio Maximo Tait.
nguyennam