Lower buds

I find whole plant harvesting is better, and the plant is not going to grow to much more after you take the top half. I would not lower light intensity unless your giving them over 40DLI.

Yes you can, this gives you also the opportunity to harvest them at different maturity grades like, 10, 20, 30, brwon trichomes.

They will not thicken up in any way that justifies it, but a more preferred ripeness can be achieved, which may or may not be important to you. I would continue to give ~35 DLI give or take... You are talking about the single most important factor to the outcome... light. Everything else should be in proportion to the amount of light you give. You could argue CO2 is this factor, but most of us don't supplement co2, so finding the max DLI you can give is the trial and error. It would be extraordinary for some perceived benefit to outweigh reducing the production of photosynthesis. It's a weak hypothesis with a low-probabilty of being proven true given existing knowledge. Like numerous other examples of bro-science - blind defoliation, long period of darkness before harvest, random flushing absent any health issues, etc etc... some people worry about light hitting bud sites instead of leaves, despite the fact there is 1/100th of the chlorophyl in flower compared to top layers of leaves. Lots of absurdities out there that are more tied to emotion and ego than reality.

My friend, dont ask. Look your garden, if you know how to make that flowers and keep them that healthy whole weeks follow your instincts. U do great job. In my opinion cut all, that parts which dont get enough light to be juicy 8 weeks anoher week with full light dont change nothing. On end i always push girls with maximum light and lower height than normal