Cardio+Weights+Snacks?

Hello all! I'm pretty new to mfp. To give a quick summary of me and my eating/excercise habits: I'm a 20yr old female, 5'5.5" and I weigh about 160 lb and I'm trying to get down to 125~130lb. I've been doing a LOT of reading and I already know the 2lb/week, lots of water, calories in vs out and what not. My main question would be should I focus mainly on cardio with a few days of light strength training to avoid muscle loss or is it okay to split my time evenly with both? As of now I go into the gym at least 4 days a week but always with an off day or two, especially after a hard cardio session (I've been doing mostly long intervals at like about 45 min at moderate to high intensity with my HR around 145-160 on the elliptical as I'm trying to build up endurance and eventually run a 5k). I don't really know how to use most of the weights machines/the names of many workouts so I've been keeping it pretty simple on strength days but I want to push myself harder because I can already feel myself getting used to the workouts. Any tips?

Also I've been having a hard time trying to tamp down eating when bored-I'm in college and sleep schedules are allll over the place so there are days when I'm up for 20+ hours and when you're pulling an all nighter in the library it's nice to have something to snack on. I've been debating going to a nutritionist for advice but don't really see the point as I'm really healthy already. Are there any low calorie (and I mean seriously low) snacks you recommend for throughout the day just to munch on? Thanks so much for the responses in advance :)