Sarong (man) and kaffetani (women) are available at the info point at the entrance. The mosque is viewable only with a guide, English speaking for a donation. Obviously not shoes . I think under the knees trouser is accettable.

Open all day but miss prayer times if not praying

Hi Hello Elodie T, Don't worry, there are private storage / lockers available, and there is a guard, sure to be very safe. Best Regards & Friendship, Java Private Tour.

Beberapa hari menjelang lebaran disediakan makan sahur, tp harus siapa cepat dia dapat

No you don't need to come in a group you are always welcome during office hours but you must take of your shoes and someone will guide you around of the official employees and if you where a short they will give you something you can use to see the mosque.

Sangat dibolehkan walaupun hanya sekedar lihat2

If you take a tour, which you will most likely have to do, there is a small area to keep your shoes (which you need to take off at the very entrance to the mosque). If you are dressed inappropriately, they will give you a robe to cover up that you return when the tour is finished.

I can answer my question now :) it takes 40-60 min from airport to mosque by taxi. Taxi drivers want 190-250 rupiah. We made a deal with a taxi driver from airport to city center tour that takes 5 hours. Driver had taken us from airport, take to the city center, we went to mosque, cathedral, and symbol of the city -can't remember name, may be national monument- We paid 600 rupiah