Hello ahmad_nafi! I also received PP request e-mail from SGVO recently and submitted my PP to SGVO through VFS-Dhaka, but I didn't applied under MPNP scheme. However, I have seen the similar problems which I also faced in my case and going to answer your questions. May the information will give some understanding to you.
1) It is very much normal. I have read the same situations in other cases in this forum. SGVO will change everything as "Approved" when they put visas in your PPs.
2) The same problem I have faced. My PP validity was 11 months and 12 days. I applied for PP renewal and put the previous PP number in new one as "Previous passport number" and submitted an explanation letter to SGVO in the same package. Also called IRCC and they advised me same, which I already did.
3) In the letter, it should be mentioned that SGVO needs 1 month to return the submitted PP and don't bother them before 1 month after submitting the PP (It is mentioned in my letter).
About "This letter is not a guarantee that a visa will be issued to you" >> I think it is a common structure of their letter. Anyway, you have nothing to do except appeal/ give explanation if they will not put visa on your PP or find any further mismatch of your documents. So, don't think too much about it. Just do whatever they are asking to do. Another thing is, you can check your online A/c and they may change with the words like "Approved/ Decision made". So, keep smiling.....
4) Finally about VFS-Dhaka, nothing is complicated there. Just follow the instructions SGVO has written in PP request letter. Bring those documents and VFS only receives & forwards the documents to SGVO. You have to sign a "Consent Agreement" for VFS. You can find it in their desk and VFS website as well. I paid total BDT 3097 for sending the documents and SMS service. I don't know what will be in your case as you are PNP applicant, but it may vary BDT 3000-5000 for each package. You can also contact with VFS-Dhaka representatives from Sunday-Thursday by Phone or Chat through their website what I actually did before went there.
Best of luck for further steps!!!