1. It is a rather tough job if you do not have a shop lift and a transmission jack. To replace the seals, it is necessary to take the tranny off the engine. You can see yourself how much labor it may be involved. At a Toyota dealer, they may charge for 10-hour labor for this job.
2. You can tell whether it is engine oil or tranny fluid by the color and thickness of the fluid leaking out. But I do not think there is much point knowing which seal is worn out since you seams having decided to fix it. When the tranny is out, both rear main seal and transmission seal should be replaced. Parts are relatively inexpensive vs labor.
