Welcome! I've been playing since 1999 like you, only I took around 20 plus years off and came back around a year ago, LOL. I was also playing 2 - 3 toons manually and it was exhausting. Then I discovered this site and community and they have made the game immensely enjoyable once again. Watch those videos Sic recommend as they are a huge help and got me from 3 boxing to 6 toons in a short time! Tons of fun playing all kinds of content when you have a good solid 6 group.
Be sure to check out RGmercs, Kissassist, and my favorite, cwtn plug-ins. All great options and you find tons of support here on the boards from this community. Hope you find this community as rewarding as I do!