Bury your produce and burn the used toilet paper for environmental and health reasons during a trek. In most cases it is not worth the trouble. Only 10 percent of Nepal has electricity. Moreover, it is very unreliable both due to frequent black-outs and occasional surge voltage. An internal frame backpack or rucksack is ideal.
Suitcases can be very inconvenient while traveling and trekking within Nepal.
Also bring along a small day-time backpack to carry around things needed while touring around during the day. A money-belt or pouch to strap around your waist for your money, passport and other valuables is recommended. Specialized gear for trekking need are available for rent in Kathmandu. I am disabled. Treks may be hard for you, depending on the nature and severity of your disability.