For events, gear level 9 is generally considered the gold standard. If you have over half your team at gear 9+ and the other 2 at gear 8+, you should be fine in any legendary or hero’s journey event, as long as you’re also leveling up abilities and giving your team speed from mods. Some events require most of your team to be at 180+ speed, and I’ve seen posts that recommend 200+ speed to unlock CLS.
Regarding ships, I would come up with a long-term strategy and stick with it. I’m one of the last people in my arena top 50 without a zeta ability because I did not plan out ships well and just starred up the ships I had until I hit a wall and couldn’t progress. I then had to plan out what I was going to do and do some serious improvement on specific ships and pilots to progress. I’d only star up ships you intend to use in arena or in challenges.