Turning Ego into Ego-T needs Ego tank atty and Ego
tanks (I think there are two tank sizes for the larger tank atty. only the small
tanks for the smaller one?). As long as the threaded depth of the SLB clone Ego is deep enough then you will not need a 510 extender. Joyetech sometimes designs their own accessories to tightly match the fit of their Ego only.
As for other attys - if you mean for dripping then Joye 306 LR is popular on Ego. I don't know what people like with carts (not 306 since its carts are small, but most people don't like carts anyway and use cartomizers instead)