লিল্লাহ — শুধুমাত্র আল্লাহর জন্য

In practice they overlap, both are voluntary. The distinction is mostly intent: Lillah is specifically for the sake of Allah with no expectation of personal reward beyond His pleasure, often given to mosques and madrasas. Sadaqah is broader voluntary charity, often given to individuals in need.

Yes, that's one of the main reasons institutions request Lillah specifically. Zakat has stricter rules about who can receive it (the eight Qur'anic categories), but Lillah can fund anything that benefits the community.

No. Give what you can. Many supporters set up a small monthly Lillah of £10–£50, over a year that becomes a meaningful contribution to running costs.