you're in soil, get it back to 6.5-6.8 unless your nutes specifically tell you otherwise.
I's not light burn, so you can move your lights back down and turn them back up before you impact yield. However, if trichomes ar less prevalent at top, you probably want to make a slight adjustment for that, otherwise right back to where you had it before with no issues...
Yes, you need to fertilize. Probably could have started a few weeks ago, but that's the fun of soil. It's all a little bit of a guesstimate... try something, observe response, and go from there. soil is always a bit of an unkown but provides numerous benefits too -- not trying to convince of anything.. i liked soil grows and likely do another one again.