I know that my gym offers free "personal training evaluations" for new members. You schedule an appointment and they walk you through the gym, explain different machines, and then do a 30 minute workout where they test your fitness level. Then you tell them what your goals are (weight loss, gaining muscle, etc), and they help you make a fitness plan to achieve these goals. When I started going to the gym I had no idea what I was doing and this helped me out a lot. I actually worked with a personal trainer for 3 months after the initial evaluation to help me figure out different routines, stay motivated, and force me into a solid gym schedule, but this isn't really necessary for everyone.
As for your questions...everyone is different, and there really isn't a "right" answer.
Can I work out every day? Probably. It's always nice to have a rest day in there somewhere, and make sure you aren't just working out the same muscle group over and over every day. If you're alternating between different muscle groups, doing cardio, etc, I don't see why you can't work out every day. I find myself going to the gym 4-6 days a week and that works for me.
How intense should my cardio be? As intense as you want it to be. I've had days where I felt like taking it easy, and I've had days where I've puked in the parking lot on the way out of the gym.
Should I do weights and cardio on the same day? Again, personal preference. I like to lift hard, take a 5-10 minute break, then do cardio. I also have days where I just feel like doing extra cardio instead of lifting, and days where I lift extra hard and don't do cardio. I don't do cardio on leg day. Nobody wants to see my sloppy ass falling down on the treadmill haha.
What should I eat? This is definitely not something I can help you with because I eat like shit most of the time, but um...healthy stuff?
Disclaimer: these are only my opinions. I am in no way qualified to be giving profesional advice and a lot of what I said could be (and probably is) wrong haha. I'm just going by my own personal experiences.
This post is way too fucking long.
Everyone has there own opions on everything. This site has a S*** ton of info on dieting, workout plans anything you can think of regarding fitness. Tons and Tons of articles and plans. Check it out.