Post preview – Single page header customization

Hello ??

I am currently trying to use Twenty Seventeen for my website (new refresh)
There is three things I would like to customize:

– In the single pages I would like to have the content directly after the header.
Currently I have the thumbnail and then with HUGE SPACE the title of the page and then again a huge space and finally my content.
I would like to take off the thumbnail and the title to get directly
Header (menu) and directly below the content I did set for the page (using the blocks).

– Being able to have only the thumbnail of the post (in the blog/post list) instead of having every single post in full one after the other.
I would like to have only the post’s thumbnail + title one after the other without all the post content.
I tried to activated the “summary” option in Setup > Reading but it doesn’t change anything ??

– Being able to have on side menu for the “blog” and an other one for the “shop”.
Or eventually Having the side bar for the blog and being able to take it of while in the shop.
Currently I have the same side bar for the blog AND the shop which is a bit uncomfortable for the user experience.

THanks a lot! ??