Approaching galactic conquest as free to play

To number 1, above, I'd say you are wasting way more energy this way. Going through with hard counters, instead of feat completing teams on your way through is costing you extra energy that could be used on your dc farm (or just less crystal use if not farming). In this conquest, every battle that is not a sector feat team should be Rebels (heaps of teams available at all stages of the game) or First Order to work through those 80 battles. If you're getting those 30 key cards it hardly matters if there are a few 1 or 2 star battles on the way.

To number 2, I think this is a mistake for FTP conquesting. No pass means no extra consumables from that extra rewards track (there are heaps). With a limited roster at lower GP, the consumables can make a big difference. Initial tether and the frenzy tech in particular can make an impossible node passable. Gong off the challenge path cuts down on your chances of seeing those, and getting to choose the more useful other boosters. It is still worth it to divert off the challenge path for that cheesy Phoenix or First Order enemy team, but only in sectors where it really matters for a feat. And in that case, I'd divert ahead of a disk choice as well, not just hope to see them again later.

I think the most important thing to do if trying to get the best rewards for your roster is planning. Go to discord ahead of the conquest and find the feat list. Figure out what you can likely achieve with your roster. If you can, look at what feats you can skip that cost the most per key card. For example, the resistance team and bounty hunter team x14 feats in sectors 1 and 2 are only worth 5 points each for 14 battles. That's a lot of energy for 5 points, if you could be doing other feats, or getting more stars off nodes along the way. But only skip them if it fits your plan.

Make sure to do a few battles for the big feats every day. I do 2 ewok battles early in the day, 2 at night. That's 4 battles at 90%+ stamina each day, to have 20 cut in 5 days. Doing the same thing for a 40 battle feat gets it done in 10 days, no stress and not really that repetitive (for this game). The 5 or 10 day time frame means you have a few days to get some disks before starting this too.

The last thing I'd like to say is about stamina management. Once you have a few sectors open you have options. If you don't have a good disk setup by sector 3, keep pushing along to get sectors done and get the disks you need. If you have an ok setup by then, you can now do a few battles in each sector each day to keep stamina high. I think of it in refreshes. Do a refresh (6 battles on hard) in sector 1 dc farming for teams that you have that can't beat other stuff. For me that is 2 ewoks and a light side mandos fight this time, then 2 Veers/piett kills fights on the Mon Mothma sector 2 dc node. Another refresh can go to moving earlier sector feats along. The third refresh and natural energy goes into progressing further. This means you are using a wide range of teams every day, spreading the stamina use, and making it less repetitive in a day.