Layout will ‘blink’ when it reloads, you can increase the layout duration so it does not happen too often (I’d also suggest not increasing it too much).
If you make changes to your layout then yes I’d expect them to be pushed via XMR to your player, assuming that you’re using 1.8 series player against 1.8 series CMS of course.
Since you’re hosting with Spring Signage, it could be a good idea to create a new support ticket preferably with the same email address you’re using in the Customer Portal.