Is it obligatory to wait for the cessation of urine or madhiy drops after urinating or thinking before performing wudu' and prayer, or is it permissible to perform wudu' and prayer immediately even if these drops continue to exit? And is it obligatory to change one's clothes for every prayer in this case? And is wudu' required for every prayer when combining two prayers due to an excuse?

You must immediately repent from abandoning prayer. Regarding drops of urine or prostatic fluid (madhy), if they are continuous and there is no time for purification, then your ruling is that of one afflicted with perpetual impurity (sahib al-salas): you perform ablution (wudu') after the prayer time begins and pray as much as you wish until the time expires, while taking precautions by tying a cloth. If the drops cease for a known period, then you must wait for that time to purify yourself and pray, even if you miss the congregational prayer. It is permissible for one afflicted with perpetual impurity to combine two prayers according to the Hanbalis. Beware of abandoning prayer, for it is a great evil that incurs Allah's wrath.