I have done everything you asked about.
I started with a Volcano (L88b, same as a Blu), and my first upgrade was a J108 (Sidesho) manual battery. The battery made a huge difference compared to the weak automatic
batteries that came with my Volcano starter kit. The
batteries are much more consistent, last quite a bit longer, and you can charge them with your existing charger or PCC. The only issue is that since the J108 batteries are longer, you cannot fit an assembled e-cig in your PCC, or close it while you are charging the longer batteries. (You may also need to trim the foam in your PCC so that you can charge the manual batteries).
After a week or two like that, I upgraded to the 306a atomizers (and carts) as well. It was then like a whole other animal. The vapor production was much denser (especially if I dipped/dripped), and for the first time I found myself able to billow small plumes of vapor that I couldn't see through.
The 306a carts are nice too, as they hold a few more drops than a L88b cart, and are capable of flowing a bit more air, due to the different design of the inner cart.
Overall, in my opinion, the J108 Battery/306a Atty combo is probably about the best you can upgrade a L88b (although by the time you do both, it's not really a L88b anymore, but more of a custom hybrid).
In the end, I used this combo for several weeks, but it still wasn't enough for me, so I bought a 510, and haven't looked back since. My wife absolutely loves the J108/306a hybrid though, so your mileage may vary.
