On the bigger board/paddling thing -
One day this summer me and the wife met up with some friends for a beach day. I didn't bring any boards as I usually don't if we're just going to chill for the day but one of the guys had a few beat up old logs so I paddled out. It was choppy and maybe waist high. I hadn't ridden or paddled a longboard in years and it was awful in the chop. Everything was a chore from paddling to turning to paddle for a wave to getting through the inside. I don't see how older guys do it. It beat me up. Maybe that's inexperience with bigger boards but everything was harder except actually catching waves. I've always held the belief that big boards are more stressful physically just from past experiences but I had forgotten how much moreso.
Just stay in shape enough to ride something reasonably sized and I think you could surf a lot longer. JMO.