Long time Civ4 player and last night I just played my first game in Civ5. Here are my questions:
1. Is there a worldbuilder option?
2. Which hotkey opens the cities summary status (F1 in civ4) and finance status (F2 in civ4)?
3. The tips mention that connecting a road between city gives a gold bonus, and railroads a production bonus. Do these bonuses stack when I build a railroad over a road and how I do check them?
4. What are some important hotkeys?
5. Can I check Ai's attitudes toward other AIs?
6. Are warmongers more likely to hate peaceful AI (like Monty hates Gandhi then anyone else)?
1. Worldbuilder is a separate program, accessed through the "tools" tab of your steam library, via the Civ 5 SDK. You cannot open up the world and look at it easily, with all the cities and units in place, like you could in Civ 4.
2. I don't use many hotkeys in Civ 5, never figured them out myself, sorry.
3. Railroads count as roads for all purposes. Typically you will want to build your railroad network over top of your roads. Keep in mind that roads and rails cost upkeep every turn, and you don't need roads to connect up resources, etc.
4. "g" for goto, "f" for fortify, "b" for build are the main ones I use. It's not a very hotkey-friendly beast IMO.
5. You can see if they are at war in one of the diplomacy overview tabs, but you can't get much more info than that.
6. Not that I've noticed. Warmongers will still tend to attack folks with weaker militaries though, and peaceful builder types will often have smaller armies, so....
). I ticked a mod every time I wanted to play a scenario and went to the "Single player" page and clicked Custom game. Then I loaded on of scenarios (or mods) that were on the list there, but I couldn't start them after I had loaded them.
Sorry for bothering you, my civilization is overall very buggy, so that might be just one of those glitches. 
