Hiding sections of layers around text and outside of shapes

Hello Guys,

Sorry for the noob question im fairly new to the application, ive been hunting around for answers but I cant seem to find what im looking for.

Below is an image of a contour map, I have 2 questions:

1.) I have added to text to illitstrate a particular peak on the map, however the the contour lines make the text hard to see. Is there a way I can add some form of stroke around the text that will hide the lays below it? Essentially any secition of line that passes under the text will stop a 2mm above the text and continue 2mm below the text.

2.) How would I go about cropping any sections of layers that fall outside of the circle? 

Thanks

Craig