For info on how I work, prices and how long it can take, please do read carefully www.cregox.com/your-home and let me know if it's clear enough.
Most of those items are a matter of implementing CSS, very possible stuff.
The arrow on last image to loop into beginning of gallery is a script for gallery, which I'd do in jQuery. Also possible, but changing any gallery behaviour is always quite complicated, partially because squarespace is still using YUI.
Moving the nav bar could be complex, I'll only know once I try.
The only point I'm not sure what you want is "plus to expand" because you say "compress". I suppose you mean making the mobile menu disappear like it happens in other templates into a compact hamburger menu button. That also could turn to be complex and I'll have to do it to know.
So, I believe I'd spend anything between 1 hour and 3 hours, but that's just an estimate.
Ideally you'd pay me for 3 hours ( U$ 369 ) and we'd go from there.
Let me know if you want a video.
If you want me to work straight on squarespace I'd need admin access and can only offer 50% refund.
In other case you either have to implement it yourself or may need to pay extra time for me to do it.
Hope to hear from you!