do not bother to solder the connections, that's old fashioned. Just make sure the terminations are secure.
The lighting project sounds very good. I would consider using the lamps in a different ratio than 1:1 2700k and 6500k. I'd use more 6500k for vegging and change to more 2700k for flowering. Maybe try a ratio of 4:1 or 5:1? Good luck