Laser watt

I,m very new to cnc/laser
I want to buy or assemble one.
I need to cut 1000mm x 540mm and 8mm thick acrylic.
Ive 2 question for now.
1- what is the min watt laser i need.
2- i see most of the cnc are smaller,if i build large like 1 meter will same cnc software do the job?