Ok, bunch of questions to answer.
How does PE work? Not sure here in a physiogical scientific sense but look around at all the odd ways humans have modified their bodies. Everything from long necks to foot binding. Humans have found ways to slowly adapt the physique to what suits them.
Does it work? Thousands say it does and some say they haven’t had any luck with it. Bottom line is to give it a test for yourself. Worst case scenario is you waste a half hour a day for a couple of months. Most would claim at least better erections in my opinion.
Permananent gains. In my opinion not without cementing. I stopped years ago without cementing and have retained about half of what I gained.
How long do gains take? Depends on the person. Many will get fast gains and some will get no gains at all.
Are there any problems from PE? Yes, you could seriously damage your penis if you don’t pay attention. Read the injuries section and other related threads like physiolic indicators before attempting. Read, read, read and then pay attention to your body.
Uncircumsized? I don’t fit under this category so I really don’t know. There may be a difference in dry versus wet jelqing but you will have to search or get someone else to weigh in on that one.
What routine? The newbie routine flat out. I am a less is more kind of guy so read the newbie routine over and over and then when you start go for fatigue without pain. Some new guys think more is better but more can not only lead to injury but also to toughening the tissues to the initial easier gains.