Is water over which Quranic verses have been recited and sidr leaves added, for the removal of sorcery, to be used cold as it was when recited upon, or is it permissible to add hot, unrecited water to it after the recitation and then bathe with it? And does bathing with it for three days differ from bathing for one or two days?

There is no harm in adding hot, un-chanted water to water over which Ruqyah has been performed. Nor does bathing with it for three days instead of two cause any harm, as there is no specific duration for Ruqyah legislated in Sharia. The important thing is that the Ruqyah occurs and is repeated when needed. Combine legal Ruqyah with complete recourse to Allah Almighty and earnest supplication to Him, for He is the Causer of all causes and the Answerer of the distressed's prayer.