You have my sympathies, I remember it well. My DC1 was only 18 months old when DC2 was 4 months old. It's hard work. I went on to have two more children, life does get easier.
So, there are several issues here and they all need dealing with in isolation.
Firstly - your 2yo coming out his room. He is in a bed then? Why? Toddlers get a lot of comfort and security from the enclosed feeling the cot sides give. I'd consider 2 to be far too young for a bed. I kept the cot until after toddlers 3rd birthday at least.
Has toddler had to give up the cot so baby could have it? Might feel pushed out or overwhelmed by all the recent changes.
Toddler not settling at bedtime - you'll need to do gradual retreat to get him to stay in bed. It inches committing to stay at his side all the way until he's asleep all the time, every night. Over time gradually increase how far away from him you are (Or DH if he does bedtime). Start off touchinh/comforting him right until asleep. Then very close but not touching, and gradually move the chair away over several weeks.
With regards to baby - if introduce a dummy if you haven't already. Feed feed feed through the day - big feeds very frequently. 2h feeds from 7am-11pm would be my suggestion. Packing baby full of calories through the daytime means fewer calories needed at night.
Bear in mind baby should be napping downstairs with you until you go to bed. Not going up without you until 6 months old. This is standard SIDS advice.
Finally, might be worth adjusting your expectations. Having a child free evening from 8.30pm makes you very fortunate. You need to reframe this as a good thing, not a bad thing.
When my youngest child was 4 months old, I had a 5yo going to bed at 7.30pm, a 9yo going to bed at 8.30pm and a 10yo going to bed at 9pm.
My eldest two children are now aged 14 and 15 and often go to bed at the same time as me. Child-free evenings are only a fleeting part of your life and soon will be a think of the past.consider yourself very lucky to have from 8.30pm adult time every single night. That sounds idyllic to me.