Some soreness is okay but more soreness is not necessarily an indicator of more muscle growth.
If you were able to do 12,10,8 with the weight you are now using for 5 reps, the 5x5 seems like it should be pretty easy. I am a bit perplexed as to how you could be more sore.
All rep ranges should be used at various points to give your body variety. Stick with the 5x5 for 4-6 weeks and then go back to the 3 sets of 12 reps.
This is mostly for your focus exercises. In other words, you cant do 5x5 for all the stuff you listed because it would take a long time, far too long to be effective. Right now, as a beginner, you should just work on full body fitness in all rep ranges, build muscle and strength in the major muscle groups. This would be your chest, upper back, lower back and legs/glutes/hips. Arms should follow from proper Upper body compound movements. If however, you find your arms are lagging behind after 6 months of serious compound exercises, then you can take 3-4 weeks and do 5x5 on the arms to bring up the lagging pieces, then go back to the compound exercises.