Generally with capacitors the factors you most need to take into account are the type, such as ceramic disk or electrolytic, the Farad rating and the voltage rating.
Circuits are designed for a specific F rating, usually in uF, or micro Farad numbers, so that number needs to match. The voltage rating is less critical, but in order to substitute you can only go higher in voltage never lower. So if your existing capacitor is rated for, say 200 volts, it's okay to use a 400 volt rated cap, but definitely a no-no to use a lower rating like 50 volts.
That being said, the ones you've found will most likely work; most components are specified within a range of allowed variation; 20% is a common number in use. The difference between a 2.4 and a 2.5 uF capacitor is only 4%, so that falls well within a 20%, 10% and even a 5% tolerance.
The 1.6 vs 1.8 uF difference is a bit closer to a 10% variance (11%, actually), but my guess is it would probably work.
As I mentioned, it would be preferable to use the exact value as the original, but if the ones you've listed are the only ones you can feasibly get, they should work.
