shud it make any differanse ,when it makes off to sketch constraints
i prefer to turn it off.. may be in some model it would help you... but most of the time it make more difficulties...
let me explain why it is used...
Answered with a tutorial: https://grabcad.com/tutorials/what-is-the-use-of-grid-in-catia-v5
yes... but constraints can be easily deleted... as i say.. i prefer to disable it so i don't have to delete unnecessary constraints..
shud it affects to constaints skech