Congrats on your 5291! Unfortunately, they really don't make a manual that is rig specific like we would hope. Most things will be dealt with pretty generically. Most of the elements of a coach are similar. It's just going to be locating and figuring everything out. That might take some work. I would shoot out a few specific questions at a time. Googling and searching on YouTube will give answers.
-The leak from your FW is likely from the drain valve. I hear they are easily rebuild-able.
-There is no "lighting" of the propane system. Once the main valve at the tank is turned on slowly to charge they system lines, each propane component should automatically light when needed.
-The two most commonly used generators used on these coaches are the Onan (Cummins) QG 4000 and the Generac Guardian QP-40
I really recommend getting intimate with your new coach. Take tons of pictures on your phone or digital camera that you can store for reference. Take all inside pictures. Stickers, switches, layouts, everything. Then go deeper. Inside cabinets, under sofas and chairs and beds. Take out the drawers, look with a flashlight for anything hidden... components, wiring, plumbing, etc. Continue taking pictures. Remove any access panels and document what is behind them again, looking at components, electrical, and wiring. All the while, be looking and note...where is: the freshwater tank, freshwater tank drain valves, low point drain valves, hot water tank and bypass valves, water pump, 120v outlets, 12 volt outlets, the house batteries, battery disconnect switch(s), water pump switch(s), slide switch(s), etc., etc.
Finally, this site isn't the most active. I recommend asking questions over on the irv2.com forum for much more interaction.