For the first 3 months all you need are multipacks of cotton zippy babygros (zip instead of popper) that come with feet (and the fold over mittens usually)
Fancy outfits waste of time, socks waste of time.
With my second I didn't even bother with a vest underneath as back to back dirty nappies in the early days just meant that was a waste of time. And they were a winter baby. You'll have the heating on anyway when it's cold because you have to do so many nappies and you just layer up with blankets.
For bedtime mine would be in just a babygro, in a sleeping bag, with a blanket or 2 over the top for the weight and warmth.
The fold over mittens that come on the baby gro are nice but I'd only use on cold winter nights or if baby has been badly scratching face. It's normal for them to suck their fingers or fists, it's a soothing behaviour they did in the womb so unless it's causing major problems I'd leave them to it.
It's also normal for their hands to feel a little cold in comparison to their body.
I erred on the side of caution as well and preferred to risk mine being slightly too cold than potentially over heating. Layers of cotton cellular blankets are your friend.
Avoid those fleecy synthetic blankets at nighttime, only use them when you need instant temporary warmth but babies overheat in them if used in the cot.
The first few weeks with your first are utterly terrifying but listen to your instincts and you will soon be in tune with babies preferences.
Congratulations and best wishes!