Mostly F2P Hero focus help plz

Randall

I spent $10, $5 for Dooku and $5 for daily crystals which I used for an 8 pack. I recognize that some chromium only characters are more powerful..but it seems that without an absurd amount of spending even if you get a few good character you are not able to star them up fast enough. So I am trying to focus on the free characters.

My Arena team:
Darth Sidious 5*, Gear VI
Luminara Unduli 5*, Gear VI
Old Daka 4*, Gear VI
Cad Bane 4*, Gear VI
Count Dooku 3*, Gear VI

Others
Talia 4* (use for dark missions)
Ahsoka Tano, 2* (use for light missions)
Jedi Consular 3* (use for light missions)
Clone Wars Chewbacca 4* (use for light missions)
Jawa 3* (use for light missions)
IG-88 3*
Snowtrooper 2*
First Order Stormtrooper 2*
IG-86 Sentinel Droid 1*
Royal Guard 2*
Clone Sergeant - Phase I 1*
Ewok Scout 1*
Ewok Elder 2*
First Order Tie Pilot 2* (soon)
Geonosian Solider 1*
Nightsister Initiate 1*

Currently I am doing
all my Arena shipments on Sidious (top 100 last 8 days)
GW shipments on Luminara Undiuli
Cantina shipments on Old Daka
Cantina missions on Talia (until 5* then going with Luke)
Force missions (I buy 2 refills per day): Old Daka, Ahsoka Tano, Boba Fett, Luminara Undiuli, Mace Windu, and Count Dooku
I spend the remaining energy on gear, however gear is getting difficult to farm for my Arena team.

Should I slowly save crystals for Chromium packs or spend what I have getting 2 Cantina refills a day?

Bit of a math nerd and planner...
Sidious will be 7* in 16 days
Luminara will be 7* in 11 days
Daka will be 7* in 50 days
Cad Bane will get replaced with Luke?/Boba?/IG-88?/OTHER? (WHICH?)
Count Dooku will be 7* in 129 days

Barriss (once I unlock her force missions) will take a comical amount of days to 7*.

Where should I spent my resources to improve going forward. What ratio do you keep your light/dark teams vs the arena team as far as gear and ability levels? I am really struggling on light side battles (5-H) and are at a wall with dark on 5-I due to massive amount of AoE damage.