For your first inquiry, Make your way to Business Central, Device Configuration page, select device configuration you are working with, Scroll down to the warehouse section, under general you find a setting called Place Bin Handling, set that to Overwrite with Prompt, this will allow the change of Bin during the put-away process.
For your second inquiry, I would recommend Making sure the column New Bin is visible on the screen during the ad-hoc movement. Make your way to Business Central, go to the applications page, select the ADHOCMOVE application, scroll down to Columns, find New Bin and make sure it is selected as column visible. I when then suggest moving it over on the handheld device so that is close to the left one of the first visible columns so you do not have to scroll over to confirm it took the bin scan. When you scan the new bin there will not be a confirmation however the new bin scan column will populate with the new bin that was scanned.