alphaod

Before my question, I want to point out many of the links in the ST sticky are broken links now and I tried searching already. Most threads are from two-three years ago and information changes quickly. Thanks!

Background:
So I used to fly basically OW only, mostly doing CX for trans pacific and AA for domestic travel [in the US], but my job has change and now I fly ST for trans pacific, actually just MU for PVG-USA. I am still doing AA for domestic, but with the changes in the CX FFP program, I don't think I can retain Sapphire let alone Emerald. Therefore my strategy I think needs to change. For many of these questions I would like to know what I should be getting as a benefit versus what is offered to me.

Questions:
(1) What's the baggage policy for ST? Is there only one priority level or is there "First" priority for DL diamond/MU platinum level customers. I noticed there is only Elite and Elite Plus, no higher level. Also do I get additional weight on the piece system? On CX I didn't get any additional benefits on CX for piece system terms of weight, but AA and JL I remember gives me 32kg/3pc no matter what which is nice.

(2) What's the policy on "premium" seating? In both *A and OW, when I had status on any given alliance airline program, I would be able to select free premium seats on partner programs. For example on AA I would choose Main Extra (or sometimes the J seats if 3-class sold as two), but is there such policies on ST? I have noticed even when I'm paying for full-fare tickets I need to pay for premium seats. I can only buy Y fare for work related reasons.

(3) What is the lounge policies? Is there F lounge access based on ST level or do I need to pay for F for this to happen?

Thanks for answering!