What is the ruling on someone who recited a complete oath formula without intention, then said "in sha'" and did not complete "Allah" (for exception), then thought he said "la" for exception? And does anything result from that? And what is the ruling on someone who swore not to wash a limb before sleeping, then performed ablution and thought that limb became slightly wet without being washed? And what if he became certain it was wet, does an expiation become incumbent upon him?

It appears you are experiencing obsessive thoughts (waswas (definition)). You must ignore them and pay no attention to them, as this is an effective remedy. An oath is only binding if the swearer intends to utter the oath formula. Therefore, your mere reading of it is not binding, and there is no need for an exception. Inquiring about the ruling on a matter does not entail anything, nor does it constitute an oath. If someone swears not to wash a limb, they do not break their oath unless the washing, which they swore not to do, actually occurs. Not every wetness constitutes washing.