The others covered the diet stuff so I'll take a stab at the other question. Pick one of the two routines in the OP (I'm on my 33rd session for the 2nd routine) and learn proper form. I have an
Evernote note compiling the YouTube videos I watched and found useful so maybe you will find it helpful. Down near the bottom of the note are videos on how to do the lifts and some tips on how to do the lifts more efficiently. Read the Starting Strength book if watching YouTube videos isn't your thing, I find doing both is helpful (especially when I was learning deadlifts).
It will be different for everyone but I stayed focus so far because I find lifting pretty fun and I have a bit more time during my senior year of college so why not go to the gym. Posting in FitnessGAF has been one of the best ways for me to stick with fitness, so much love, support, and inspiration here. Additionally, I watch fitness videos on YouTube; it's hard to explain but because I invested a lot of time into fitness related media, I have to make the most of it.