Very basic and specific questions about IP.

I apologize if this is not the place to ask this questions.

I have been studying for N+ exam but I have some concepts that I cant grasp my mind around.

1)Everytime I turn on my computer, does it get new IP address? If so, who assigns me this IP address? I know that DHCP server assigns it automatically but where is that DHCP server? Is it in my router? Did it by itself decided what is my IP scope and subnet mask?

2) Same question about DNS. I understand that it maps domain names to IP addresses. But where did it get in my computer? is that in my router?

3)If I have a network of 10 computers. Do they change addressed every time and then notify DHCP or does DHCP keep track of the addresses that changed?

4)In large networks, are there computers just dedicated to DNS and DHCP? or do they run on the same computer? or do they run on a computer which is also used for someone at the help desk. also, if they do , do they look like a regular computer or is it anything different?

5)Subnet musk is logical division of the network. If I have 2 groups of 5 computer each and they are in different subnet, how would it be possible for them to communicate? if it is possible please explain how. Because, if they are different logical groups and one is not allowed to talk to another, is there NO way of communicating in case it is needed? (i think this is the dumbest question of all)

Again, I am a complete dummie in this subject. I just think that if books or videos explained BETTER how things work and why do they work like that, and showed a real life example I would understand better. I just want to really understand these concepts because I find it hard to move on to other subjects since these are considered to be basic. If i will ever have a job interview and someone asks me "what is IP address" I know that "its just an address like your house you know....but on your computer" is not going to be enought.

If anyone is willing to answer my questions I thank you a lot