Plasma Turrets have a greater DPS than titans. The use of Plasma Turrets is recommended
Titans have AOE damage that might change this. Tesla Turrets can do more total DPS to a large group, but less to a single target, and thus could be better.
Arc turrets are cheap and good anti land for the start of the game, and their ammo is energy. Great against early waves. The only problem is that in early game, large amounts of power can be hard to come by.
Get stone a lot early game
This one is straight forward. Spam Stone Drills and Conveyors. Recommended for Purge since you need a lot of materials.
Spam Double Turret/Turret and Stone Walls for your defensive lanes. This deals a lot of damage early on and makes Easy to Hard early game non existent.
An effective way to merge conveyors. This won't prefer one line over another because the two inputs come to the middle conveyor perpendicularly.
To be added later
So if you want to create batteries use lasers and power boosters. you will need a large area to work with and it will take a lot. But it will work for the time being. First you make a line of power boosters however long you want. If you want more than one make them one block apart. Then in between the gaps add some thing like a laser router.
Placing a smelter or a crucible next to a router placed on a conveyor will provide all needed items that are placed on the belt. It is the most compact way to make a smelter/crucible system and it will never clog since a router does not give item to an entity that cannot recieve more of this type of item and will just follow its course
(# = router, ◘ = smelter/crucible, > = conveyor)