Several beginner questions I haven't found answers to.

I've read most of the FAQ posts here and some of the beginner posts elsewhere but I still have some unanswered questions.

1. Does getting 3 stars on an AI battle gain you more loot than getting 1 or 2 stars? I understand that getting 3 stars on a battle at least once unlocks the ability to use sim fights on it later on, but is there otherwise any other benefit to getting 3 stars or can you set a fight to auto when farming even if some characters might die and you get less than 3 stars but still win the battle?

2. Do sim fights give a greater chance of loot than regular fighting? Any benefits other than time saving?

3. How do rewards work when borrowing allied units? Currently I have one friend and when I borrow their units, I get 20 ally points. If I borrow a random person's unit, I get 10 ally points. Do my friend and these random people also get ally points from me using their units?

4. How often do friends' units get offered? I have that one friend and one of his units only gets offered maybe once every 20 minutes or so. If you have more friends, do they get offered more often than that? I tried requesting to be friends with around 20 people from the last ally thread and all but one rejected so I'm guessing there are downsides to having low level friends.

5. I've read that you should not level worse characters because it'll take away resources from your main team, but up to what point is it generally "safe" to level lesser units to? For example, units like Talia, Jawa, Royal Guard that I don't plan on having as part of my main team down the line but currently are very useful for filling out my squads - I'm currently keeping them on pace with my main team units (only level 30 currently). At which point should I stop keeping them at the same leveling pace and start saving credits instead?

6. If an item or shard is available in 2 or more different missions, is there a difference in drop chance between them? For example, Jedi Consular shards can be found in both 1-B and 1-D. Do they both give the same chance for getting his shard?

7. Is there a resources for finding best/most efficient spots to farm certain heroes? I've heard things on this sub like "you shouldn't farm Luminara in x because she's more efficient to farm in galactic wars" but is there a list of things like this somewhere?

Thanks.