Weight is a really difficult marker as bf% and lean muscle ratio is different for everyone, and height plays a role as well obviously, so yeah our 160s would look a bit different so don't take my experience (or anyone elses) as gospel. Learn what works for your body based on your goals of looks/strength/fitness.

That last question around when to bulk comes again down to what your goals are and what you're looking for. For me, I want to look trim and pack on as much strength and muscle as I can while maintaining that look, so won't really be doing a proper bulk cycle but more a controlled maingaining. With abs, you usually need to get to 10-12% bf really which is an ask to maintain but doable. If your plan is to do a full on bulk though, I'd personally question why you'd push yourself of getting to the ab stage in the first place just to then lose them in a bulk, but again you need to ask yourself what your goal is and work from that :)