For my weekly routine, on my workout days should I focus in one specific area just for that day? Example; on mondays I would just train my upper body.

Also how many reps and sets are suggested for a beginner?

Read the stickies mate! This is wayyyyyyy to much of a broad subject to give a good answer on that question once you have read those stickies im sure you will be in good stead to ask some questions we can give some decent answers for good luck

As suggested read the stickies and include compounds rather than isolation exercises. Leave 48 hours before hitting the same area again ie if you do chest on Monday don't do it again till Wednesday.

I find that doing a warm-up and then doing the bench press is better than doing cardio/HIIT and then doing the bench press last when you have no juice. Your mileage may vary.