Hello i am new to Maya and i am following the Intro to Maya 2015 by digital tutors when i was at Dynamics section…I faced Some problems please answer them by one by one

01.after i emit the Nparticles from a object they stop emitting at about frame 40 or so…but The tutors Nparticles are Keep emitting in every frame (they go Up up up and so but mine stop at frame 40 and they staying there not emitting…so how do i fix that??
02.The tutor used Mental ray to render the Nparticles But my Mental ray isn’t rendering them (i used Harwere 2.0 and it worked but I need to know how to render them with Mental ray cuz TUTOR did it

Thanks pls answer them One by one and be Descriptive and Don’t use Advance words IM NEW TO MAYA
Thank u all have a nice day