I levelled once to 60 on a private using the joanas guide, it was a complete 1-60 guide telling me exactly what to do I had fun but felt I was to "stuck" to the guide, a few months later I decided to level up again, but without using any guide I just followed where the quests took me and if I ran out of quests I would goo to a new zone with my level, I had the time of my life, so my advice is do what you find fun, I would recommend playing the first 1-60 with no addons, in the end you'll probably only waste 10-20 hours if you don't use the optimal path and you'll have more fun.
I really don't agree with you on the DBM matter, I think it will work as it did back then since now most encounter are based on scripted set timer that happen to the second, in vanilla it was a lot more random, you could know what was coming next, but the timer were never correct it was more of an heads up of what was happening next.
I believe that these server are going to be really successful and blizz will eventually release TBC and WotLK
It defensively won't be like the original experience, but it will be close to it, you'll still make lots of friends, invest a lot of time to progress, feel accomplished when you reach 60, get excited about loot again, etc, the core of the game will be there