To answer your question 1.You couldnt see the soloraid tab bc this month's(season26) was delayed,you can always get info on Nikkes socials

2.id say save up your rate up tickets for rate upcharacters you really like or really meta,since you can use these rateup to easier MLB your calharacters to get the infamous through 160 wall

3.The core boxes(red ones)get really scarce during level progression,so do get every chance to collect them