I like the idea of this thread. It provides an alternate topic to talk about for a change, and everyone can potentially brush up on their background knowledge.
John Martyr, on 04 October 2012 - 09:47 PM, said:
1. What kinds of planets are there in MechWarrior? Can every planet be listed in enough time for you to list them all for me? If not, what are the most important ones?
There are way too many planets in the Inner Sphere to list them all in a post, especially with detailed information, but here is a map for you:
http://www.housekurita.org/InnerSphere.png
A word of warning, though - it takes some time to load.
In terms of types of planets, most colonized planets tend to be somewhat "earthlike", but obviously there are some variances in temparature and gravity. There is/was some terraforming going on, too, but since the tech-level has dropped such projects would probably have become somewhat rare, and on some worlds the population has a great tendency towards mutations due to flawed terraforming.
As far as the most important worlds right now are concerned, there is of course Terra itself (currently under ComStar administration), then the various factions' homeworlds, and the planet of Solaris which is famous for its gladiator-like mech fights that get broadcast all over the Inner Sphere. I recommend looking to sarna for specifics.
John Martyr, on 04 October 2012 - 09:47 PM, said:
2. What are 3 search terms of MechWarrior concepts I should definately do a search and read up on?
Are you referring to Battletech terms, or pilot characters? In case of the former, I would say "Inner Sphere" (which will lead you to the various factions), "BattleMech" (for technological fluff) and "Mercenary" (as this is a role you can play in MWO as well, in case the bigger factions are not for you).
I would recommend reading up on the Great Houses of the Inner Sphere, as well as potentially the Periphery Nations. They have very characterful cultures that may greatly influence your choice of faction for this game!
Also, have fun in your further research - you have taken the first step into a great and thrilling setting with lots of interesting background about awesome battles, high ideals and dirty political schemes. I was fairly new to the franchise as well (only played MechCommander 1 & 2 many years ago but never quite got into it beyond these games), until MWO piqued my interest. Once I started reading, I could not stop - and now I own several books of the tabletop and the RPG, simply because I truly enjoyed absorbing all the detail.
Speaking of these books - the "Handbook" series is a great read once you figured out which faction interests you the most!
Yoroshiku!~
Aym, on 05 October 2012 - 04:34 PM, said:
It's like 40K but the Emperor is Alexander Kerensky and the Imperium of Man is the Inner Sphere and it's all political and the Clans are the like Elves, everything you can do they can do better.
What...

Kerensky was a general, not a political leader. Unlike the IoM, the Inner Sphere is also fragmented in numerous nations with no overarching leadership - unless you are referring to the Star League era, but I'm fairly sure OP would like to know what's going on in the "current" century.
Edited by Kyone Akashi, 05 October 2012 - 05:17 PM.