League of Legends (LoL) Question: About runes

Kind of a late response but:
Use op.gg as one of the most reliable average setups for your runes. You will learn the runes for your champions over time, but op.gg is helpful until then. You can also look at guides here on Mobafire that explain the runes and why you take them on different champions.

There are not really champions that have super similar runes per se. Some adcs/adc lookalikes have similar runes for the main page, but will seriously deviate for the secondary page.

I would just like to add that, the way the new runes can be exploited is really wonderful, and I think to some extent there are almost all possible combinations that can fit any champion, while you will always see in guides a few best ones that might seem perfect for a champion or commonly used, it is not set in (key)stone exploring the runes on your own seem much more entertaining and fun.

Maybe my answer won't be what you're looking for, but I think it's the best I can give. There is no way we can detail all runes uses for every champion, matchup and situations. It's something you'll pick up over time. So I suggest you look up the champion you're going to play on probuilds and just use the same runes. As you use different runes, or as you look up guides or videos, you'll learn their pros and cons. But I think it's not realistic to learn everything about it at once. Wish you luck!