Regarding trekking polls on the trek; mostly the elderly age trekkers are using them; it is worthwhile walking down hills and climbing. We suggest you batter to use trekking poles for the trek, this will good support while walking on snow and slippery trail. But it depends on your comfort also, how you feel more comfortable either way. The trekking poles can buy at Kathmandu at a reasonable cost (for a pair 7 to 8 USD to above depending on different quality).