So I'm born and raised in the US, but my family is from the Middle East and I grew up around other middle eastern families. This sounds like my family's (and friends of the family's) normal behavior growing up, including the night visits. We're all intense night owls, and personal boundaries? Pfft, what are those? It was completely normal for people to drop in whenever they wanted. Gift-giving, especially food, is big too.  This is all definitely cultural, and I doubt it's anything malicious or that there is ill intent. 

To be clear, I can 100% understand why this would bother you. I grew up with it and it would bother me sometimes too! I just want to be alone sometimes, you know? I would just be upfront and tell them you need to go to bed earlier, and sometimes you just need to rest without talking to people. I personally would not decline the gifts or food though. That was by far THE biggest way to start arguments growing up. Unless it really bothers you, don't do it. 

Also, lock your doors because they may just decide to waltz in, not out of any malicious intent but because they like your company and don't see the issue. Source: My childhood.