I see that you have found the embassy in London's website. I would check very carefully before using info from them. I found when looking into Visa on Arrival that the various embassies gave different information.
I took the Ministry of foreign affairs site as being the most definitive.
http://kemlu.go.id/en/pelayanan-keko...n/Default.aspx
I don't know about the transfer to domestic but the international arrivals at CGK have been painless for me with enough signs etc to find the right lanes etc.