You say you've camped and hiked "a good amount" before this, but the rest of your post makes it sound like you have no clue about how to begin or what to think. Whew! This is a bit confusing.

It will be easier to help you if you get a bit further in the process of sorting out your thoughts and your plans. In the meantime, I am sure you will get some good, but rather general advice to help get you started.

Reduced to its simplest essence: you will need to eat, drink (water), sleep at night, and protect yourself from getting too hot, too cold, too sunburned, or too blistered to hike. The main thing that is hard about this is carrying everything you'll need to accomplish all that.

Since you are going with an experienced backpacker, it will be in that person's interest that you not make a lot of mistakes, since they will be the one who will be most likely to share the cost of those mistakes. Ask your hiking partner for a packing list to help you plan, with special attention to how hot it may get, how cold at night, and how much water you will need to carry. Hint: water weighs a lot, so getting the right amount is pretty crucial.

As for advice on what pack or sleeping bag to buy, it is too soon in the process to give you much advice. Good advice would depend on a many factors. Will you future trips resemble this one or be in entirely different environments? Will they be as short, or would you like to hike for more than one night? What do you already own? Do you have a lot of money to spend?