Max seems to have got the time wrong on that first question. Yes, either of your options is correct, although I wouldn't say 'a little bit'.

If I had been in a bar for an hour with my friends and it was evening and I had stayed home the rest of the day how could I express that? Can I say :" guys I really needed to hang out a little bit with you I've been /was home studying all day"? For this first question you could say It would be great to hang out for a bit. I need a break as I have spent all day at home studying. If I hadn't seen someone all day and it had been quite some time since we saw each other how would you say: "I missed you so much, I haven't seen /didn't see you all day". For this one you would say. "I missed you so much, I haven't seen you all day" If I had just finished eating would It be ok to say:"I was so hungry I haven't eaten all day"? And in this case you would say. "I was so hungry, I hadn't eaten all day" Please book a lesson with me if you would like to practice more :)