It's not necessarily skippable in that you completely ignore it, but there is a "SKIP>" option at the top right when going to a stage to skip over all the retarded dialogue. I mean, I guess technically the campaign is skippable in that you don't have to do it, but it's one of the best places to grind for unit promotion mats. It'd be extremely difficult to only rely on the friend and commendation shop - not technically impossible, but it'd take significantly longer to promote. But, you only need to go up to stage 3-4 to get the last piece you need for base level 3. Which is pretty much "endgame" base level in the current content.
The thing that is great about this game is that each "role" can be filled by its 3*, 4*, 5*, or 6* variant. Getting the 6* variant of a particular role just makes things easier/gives you more room to "fuck up". You get a guaranteed 5* on start(might be a 6* as well if that banner is still live). Silverash is probably the best "overall" unit in the game, but he's only 1 "role" filled on a typical team. Plus, guards aren't useful on certain stages. I wouldn't worry too much about rerolling, honestly.
Jesus fuck, that's insane luck. That reroll of Silver Ash, Angel, and Hoshi is just nuts.
Yea it was really lucky haha. I had an emulator setup at home for rerolls but I tried one summon when it released on my phone and it spit that trio out. Seen many "youtubers" rerolling 100 to 1000 times for 3 6 stars.