Hey zoid. Glad you finally got the game. Hmm... I don't think you'll have a difficult time playing this game since you've played EO4.
But some basic rules to keep in mind:
1.) Fuuka is the better of the supporting characters since she has a leader skill that heals HP every turn for very little cost. So she should be you supporter in-battle and Rise should be your navigator. Fuse their sub-personas with those roles in mind.
2.) Physical attacks are waaay better than magic in this game. Magic uses mp to cast and mp can only be restored by using items or the recovery provided by sub-personas after battle. Physical skills can be restored by Fuuka's skill, items, and sub-persona recovery. But physical skills deal heavier damage later in the game because you get access to multi-hit skills and crit increasing passive skills.
This doesn't mean that a party of magic casters can never win battles. It just isn't optimal because you're gonna have to constantly go back to the base to heal your mp. And the more "powerful" spells cost a lot of mp but do a fraction of the damage of physical skills. Magic casters are still useful for casting debuffs, buffs, status effects, and ailments. Dealing damage is just their secondary role.
3.) Naoto is the most loved/hated character in the game because she learns the insta-death spells hama and mudo naturally. None of the common enemies in the game are immune to both elements, so she can basically kill off a couple of enemies on her turn. And she usually goes first because she has high agi. If you couple that with the Impure Reach skill (which increases the chances of landing status effects and insta-death spells), she can end a lot of battles on the first turn. You can also do this trick with other characters in the game, you just have to set-up their sub-personas with the skills I mentioned.
4.) Impure reach is definitely the most important skill in this game. Even if you don't want to use Hama and Mudo, status effects are important for dealing with FOEs. FOEs in the first 2 dungeons are easy, but starting from the 3rd dungeon, they have really high evasion. So inflicting them with Panic/Agi Bind is a must.
5.) Keep fusing sub-personas. If your character's level is 5 levels higher than your sub-persona, your stats get penalized (I think your damage output decreases by a certain percentage). I usually fuse demons when they've learned all their skills.
6.) Remember that you can "save" demons you've fused and trained to your compendium. This allows you to keep a record of a demon (even if you've already fused it) so you can summon it later on for a fee. This is important if you like a skill and would like to keep passing that skill on for later fusions.
(2 System restores after crashes and multiple contacts with detal later 