No autographs or photos included in Lieutenant and for the Commander one, only autographs - two are assigned (1 assigned tier 1 guest, 1 assigned tier 2 guest and 3 vouchers worth £15 for the guests charging that amount - i.e. Alice Krige, Marianna Hill, Hannah Cheesman etc.). I'm guessing this year the tier 1 will be George Takei, Kate Mulgrew, Jeri Ryan or Doug Jones. They email you closer to the event in terms of what autos/talks you get. It seems to be a good package for the overall experience but not great if you have specific guests in mind. However, having said that you have an easier time queueing for autographs with Commander.
I'm thinking of going for Commander because of what's included over the weekend and the perks and maybe getting one or two things on top closer to the event. In previous years when I was thinking of going I figured a three day pass was a false economy as it didn't include any paid talks or parties. However, to go for just a one day for specific guests you're probably better off just getting a day pass and getting things individually.
Re the parties, looking at comments I've seen about previous events they were held at nearby hotels and I'm sure recall seeing comments about some actors being at them. I know Tim Russ' blues band played at one a few years back. This year they're being held at the Excel itself. I wouldn't be surprised if it's a bit different because of Covid. I'll probably head to them though as you're right, I'm sure I'll get talking to people at the event!