The instructions will tell you what OS wants you to run in there engines with both nitro and oil %. Sense Power Master is no longer around we have been running Wild Cat and it does only have 16% oil. Due to the engines I run I gave the oil percentage a lot of thought and started adding 2oz. of Klotz oil to the Wild Cat. The debate of Castor or no Castor has been ongoing for years. I have tried it all and not noticed a nickles worth of difference. If I ever run an engine so lean that I'm going to do any harm that Castor is going to save it then I have really messed something up. If you look on the label it will state {Usually} if it's a blended oil and most blends have some Castor in it. The Klotz oil I add has 20% Castor added to it's blend and the Wild Cat is also a blended oil. I like a blend with the Castor in it but not for lean run protection, more for cooling and the way Castor leaves a bit of a varnish coat to the inside of the cylinder and how well it leaves that extra rust inhibitor behind.
Batteries, I get about 4 years or better out of all my packs. Not having any real off season my planes get used all year long. I do cycle but for the most part it's to check the condition of the packs to see if they do need replacing. the instructions will tell you all you need to know, just follow them.