Rezone search and create single line menu

Hi, I’m a newbie and have inherited a site – https://animalstudies.org.au/ to look after. I am hoping to do some basic visual updates to the template. I’d like to move the search functionality to the bottom of the pages [I’ve worked out how to remove it from the header thanks to previous forum posts – although it is still there presently until I can place it elsewhere].

Secondly and I guess most importantly – I’d like the menu to span the full width of the page – to avoid the menu becoming two lines [which is interfering with reading the current page headers].

I’ve had a look – but the advice I’ve seen doesn’t seem to relate to the Conjuction theme we are running.

Can any one provide assistance? – I have some basic html [once a webmistress in 1995-6] and I’m not too afraid of testing things out and reversing my work. Many thanks!