It's very hard to recommend the right mouse because it's such a personal piece of hardware. Many enthusiast PC gamers including myself go through a lot of different mice to find one that works best, but it may not be the same that works best for someone else. There are so many variables, including grip style, hand size, personal preference, mouse sensitivity.
"Gaming grade" keyboard and mouse are by no means necessary, you can get by with a good old office keyboard+mouse combo as well. But the user experience with a gaming keyboard and mouse is simply better, even for someone new to PC gaming.
What kind of games do you play? Some peripherals are better for specific game genres, particularly MMO's versus FPS games