What's the policy for a executive lounge guest that isn't staying in the same room as me? Would they even check? This is for a Marriott property in London
I am staying myself in my room, and would like to guest a friend (gold) who is staying in another room. Is this possible?

It's hotel specific. I've been able to do it before (at a Washington DC hotel) --- but it helps to have your reservation show two guests (and not just you.)

No harm in trying.

I have a question. Some of you have experience with early arrivals (sometime before 12pm). I read in some threats that some FTs are booking on day before they arrive so they could get into the room when they arrive at the hotel. How do you handle the checkin process or getting a room key? I'm thinking about doing the same as I have some early arrivals but never did so far. I appreciate any good suggestions or how to's.

In this situation I check in online and contact the hotel through the chat function in the app (on the day when they expect me) to let them know that I will only arrive the next day (and at which approximate time). That has always worked; they thank me for the information, and I get the key from the front desk whenever I actually arrive.

This sounds very simple. I think I have to try this out exactly the same way. Thanks for sharing.