I am on Chapter 27 of Hard/Classic Conquest, so I am at the end. The last several maps (including paralogues) were very tough, and required some restarts. However, all Conquest maps will go much faster on future playthroughs now that I found strategies.
Main non-child units: Corrin, Xander, Kaze, Niles, Elise, Effie, Camilla, Leo, and Silas are all level 20. Felicia and Azura are both level 35. Charlotte made it to a level 10 Berserker, but she was dropped because her hit rates and durability are absolute trash. She is bad unit who is only good for Rally Strength and pair up, so I wasted a lot of EXP on her. Every other unit stayed on the bench due to EXP constraints. I know some of you guys used different units than I did, and I am very curious about them. I would check out the other units and children on a different playthrough for sure.
Children: My child units are all powerful and range from level 15-20. When added to my main team, I have about 13 strong combat units and 5 strong support units. I unlocked paralogues for Shigure (Azura), Midori (Azura), Sophie (Camilla), Percy (Effie), Nina (Nyx), Siegbert (Luna), Ophelia (Felicia), and Dwyer (Elise). I could not think of any suitable wives for Corrin and Leo, so they are both bachelors on this file. They can hook up with somebody on a separate post-game file. I restricted support building solely to the main chapters and paralogues (no castle grinding). The pairings were generally not planned, and some of them formed at the very last minute.
Gold: I struggled with gold for a long time, but the last two chapters gave me 30,000 gold combined. Percy and Nina's paralogues also gave me a little extra. Now I'm rich! The really good items are still expensive, but I can definitely buy what I need to complete the game.
Basically, Hard/Classic Conquest battles are challenging. If you concentrate on a core team and set of relationships, you should have enough resources to get through the campaign. The paralogues help a lot, and you can get a massive boost just by doing a few of them.
Lunatic/Classic sounds like a nightmare, though. I do want to try Birthright, but I'll be taking a small break before I do that.