Wow, it's great to see all the new people posting recently. Welcome to distance running (the way you say this, did you happen to be a sprinter in a "former life"?) and Hillrunner.com.
As for advice, you bring up four things specifically:
Workout plan: When first starting out, the best plan is to just get out the door as consistently as possible. Just get out as many days as possible for 20-30 minutes a day if that's what you're ready for. If you aren't ready for 20-30 minutes, work in some walking breaks (alternate 1 minute runs with 2 minute walks, 4 minute runs with 1 minute walks, or whatever balance is right for your current fitness level) so you can keep moving for that amount of time. Over time, you can phase those walking breaks out. When you're consistently running 30 minutes a day more days than you are not, stop by and ask for more. Until then, I think it's best that we don't get too far ahead of ourselves. Of course, if you're already there, feel free to say so.
Supplements: There's a lot of debate about this. My usual suggestion is eat a healthy diet with a lot of fruits and veggies, take a one-a-day if you feel the need, and don't bother with anything else unless you have a specific reason for doing so.
Shoes: You could ask 10 different people and get 10 different answers. The correct question is what is the best pair of shoes for you. To answer that question, if you have one available, I'd strongly suggest going to a specialty running store and having someone who knows what they are doing work with you to find the right pair of shoes. They should have you try on several different makes and models and not pressure you into any specific one.
Cross-training: If you're looking to improve your running, I'm a firm believer in the concept that the best way to become a better runner is by running. For most of us, cross-training is just a use of time and energy that could be better used to run more. If you're looking for general fitness gains, nothing is off the table.
As for other advice, don't try to push things too quickly. The body can do wonderful things but it takes time to adapt. Give your body that time and you'll be surprised what you can accomplish. The number one rule of being successful in running is patience. Number two is consistency.
If you have any other questions, don't hesitate to ask.