Honestly, I HATE playing RDM under level 70. Without access to Verflare and Verholy, it just isn't satisfying to go into the melee combo. It feels like I'm barely gaining any dps than if I just sat and casted the entire time. But like someone previously said, there is always PotD if you really want to start something at level 1.Not that it helps now, but I think that all the jobs should have started at level 1 so there's an easier time to learn and a better possibility for more competent players in high level dungeons.
And as to the sometimes your Dualcast didn't proc. Remember that it only procs off a hard-casted spell, not a specific spell. To exemplify this example, the opener has you hard-cast a Verthunder/Veraero and use the Dualcast proc on the other. In normal play, you wouldn't hard-cast one of those 5s spells, but in an opener with a countdown, you have the time so you might as well get the extra potency and colored mana. Also to keep in mind that lag is a thing. The best thing to do is to reduce lag, but if you can't, you learn to play around it (or find another job that isn't affected by lag as much). One tip would be to stutterstep each hard-cast to reduce the lag impact. When a spell has about 0.3s - 0.5s left of it's cast, you start moving. Your character will still continue the cast, but you can get a little movement in and be ready to start casting the moment your GCD comes back up without having to wait for the lag between casts. This is even more helpful for RDM because it gives the server a little longer to register that you have a Dualcast proc. But lag can kill any job, not just RDM, it's just something you either fix, or learn to deal with. For example, I used to raid on AST back in HW and SB. At times, I would lag when I used the Draw ability, the ability would go on CD, but I wouldn't have a card.