I agree with most of the previous posters but would also suggest that your 2.5 year old needs opportunity to explore and get to know his new one year old brother. Provide plenty if opportunity for appropriately touching each other; stroking, brushing hair, hug to each other at bedtime ( if 2.5 year old okay with this).
I think his reaction to little bro/ new person is very normal ( at this point in time). I have three children under six ( two BC and one AC). When AC joined our family Bc2 was 2 years and 9 months, AC was one . BC2 went on hunger strike! Getting to know this stranger, to share his toys, having his space invaded was big news. In your case Dc1 has had his space completely changed/ removed ( very recently), everything familiar turned upside down etc ( see Kew 's post- I agree with her). What I would add is, this new little person will seem like both a threat/ curiosity and interesting toy all at once to your DC1. Pulling of hair could be met by, 'you can stroke his hair gently, but don't pull, see like this'( model stroking). Rolling on top of him ( in my experience) is about trying to initiate a game/ seeing what happens- (loud cry of protest usually)/ copying or mimicking baby. You could meet this one, for now, with 'do you think little 'x' can roll too?, can you both roll the same way?'
Your 2.5 year old isn't sure how to react/ behave at the moment, so he's possibly looking for cues from the baby. He's also probably feeling uncomfortable sharing his personal space. My dc2 was appalled at first when the baby crawled over him, and, shock horror, when she snatched a toy. He screamed in fright. He too gave the odd push, would snatch back frequently, or initiate snatching to see what would happen.
Slowly the children relaxed into each other's company, very slowly.
My advice is,when your children are together try to praise them for positive physical contact, like waiting a turn with a toy, a nice cuddle, and when the older child gets close to the younger try to relax and let him explore his brother before you stop him; otherwise little bro will become a curiosity piece , all the more interesting ( don't let him hit, but don't assume he will always hit, if you see what I mean). Also try to ( in a few more days maybe), show dc1 that you trust him with Dc2; leave the room and let them be together alone( watch where they can't see you). This shows dc1 that little brother is just there, normal, everyday, and not something super precious and to be protected ( by you). At the moment it might seem to him that you're guarding this exciting treasure, the baby!
Trigger points in the day of jealously for us were after Dc3 woke from a nap. Prior to this, dc2 had had me to himself for an hour, and transitioning to that 'sharing' time again was not welcomed ( and still isn't!) To cope with this, I remind dc2 that nap time is about to end and have an activity prepared ready that involves Dcs doing an activity together, eg playdough, painting etc. something where the focus is still on older child but younger is involved .
Also, bath time! I have found with all three children that bath time together provides a fabulous opportunity for helping new siblings get to know each other. Sit them opposite each other in the tub( in the bath they sit in a tight space so are forced into each other's eye line- promotes great eye contact). Lots of bubbles, allow touching of each other to brush bubbles off each other etc. The baby will probably delight in this water play , pouring water on each other etc, and the older can be in charge of gently pouring.
Finally, just to add to what posters have said about the going to bed issue; yes it sounds like resistance to bed, but also sounds ritualistic. Ac used to rub herself and bang head on cot bars as part of her ritual to get herself to sleep. She would also headbutt and kick me, and still does, as a way if saying 'put me down in my cot, I'm tired, please let me sleep' . If I try to hug her for too long she'll kick me- it's an intimacy issue too. The intimacy for her at bedtime has to be, and still is, on her terms. ( she's about the same age as your dc1 now). We continue to work on this, but I'm happy for this to be on her terms as slowly the hugs are getting longer.
I hope these practical ideas help. Sounds like you're doing a great job, keeping plodding on, and a huge well done on finding a minute in your day for Mumsnet posting with that age gap, as that's a huge achievement!