Hi, and welcome to the Fly Fishing Forum.
IMHO, your friend is correct about reels. For the type of fishing you describe, mainly light warm-water, a modest investment in a reel will suffice. Make sure you add backing to your fly line, to give you a margin of safety should you tie into a long-running fish.
As to the right line: I'd get a floating line in a weight forward taper matched to the weight of your new rod (5 wt). Again, you can get by with modestly priced line, given that you'll be using it on lawns and driveways on occasion. Avoid really cheap lines, though, as it's hard to learn and get the feel of fly-casting if the line isn't finished and tapered properly.
Also, get some tapered leaders to attach to the end of your line, and you should be in business.
You mentioned learning to cast. Be sure to get expert instruction before you build improper muscle memory into your technique. Most fly shops offer instruction, and it's really worth it to start off right. It takes much longer to unlearn bad technique than to learn correctly in the first place. Remember: practice makes permanent.