1. In general, using the same champs everywhere is probably not a good idea. The different dungeons need different strategies to beat. For example, turnmeter reduce is very helpfull at Fireknight und Spider, while Dragon and Clanboss are immune to this mechanic.
2. Your Soulbond needs other gear. Turnmeter reduce needs accuracy to work, and her A3 with 100% reduce is one reason to use her. I used Soulbond in my Fireknight team in addition to Armiger to hold the shield down.
3. You have a lot of champs allready that are worth lvl 60. It's a massive grind to get everybody to that stage. I would do only one champ at once, otherwise you end up with a roster full of lvl 50 champs and no lvl 60. I recommend to lvl up the following champs: Fellhound, Ninja, Sepulcher Sentinel, Frozen Banshee, Sinesha, Black Knight, Fenax.
And yes, I would do Fellhound first. With strong equip, he is one the fastest campaign farmers in the game, he can do 12-3 brutal in 6 seconds. That makes the progress of levelling up all the other champs much faster. In addition to that, he is strong at Fireknight, with his reflect damage skill.