oh it's been a while since I took a look at the game's affection paths. I know it's for sure possible to have everyone at the festival and get the 'good ending'.
I think if you want to specifically get Drackey as your end partner, you can complete his second date but avoid as many other's as you can. Completing the second date gives a big bonus to affection. Completing the first also gives you a small bonus.
Most dialogue options will have small impacts, and as you said clothing can help slightly. The cowboy and tactical outfits are best for Drackey.
To get characters to show up at the festival, that pair needs to have agreed to help with the final assault. And for that to happen the sum of those characters affection needs to be more than 8. So for Kase and Corsica to help, they need to have at least 8 affection together. Kase could have 20 and Corsica could have -5 and it'd still work.
For Blinki to show up, he needs to not die (obviously) and for Liukhalo to show up, he also needs to not get shot, and know you can still be friends.
I linked a very old, most likely wrong, affection summary. At one point this was accurate in keeping track of which scenes had dialogue choices that'd affect character's affection towards the player. I don't think I kept it up to date, but it might give a vague idea of when and where some of the affection comes from. (for the person reading this months after I posted, there's a good chance this link is dead, sorry)
https://docs.google.com/spreadsheets/d/1G5KLh_wJFacgfE4nxwkxSeNFj6Z9o_d8/edit?us...
Hopefully that helps a little. Sorry I couldn't give you a more direct path but good luck! And I'll put those bugs in my bug reporting document and hopefully some day get to them x3