I'll take a stab at your questions:
For more lavender you need a lavender male or split to lavender male over lavender or split to lavender females. With one lavender parent and a split parent you will get 50% lavenders and 50% lavender splits.
With two split to lavender parents you will get 50 % lavender splits, 25% lavenders, and 25% non lavender splits.
As far as a chocolate male for your blue female what are your color goals? This pairing will give you blue fawn and chocolate females and blue and black males split to chocolate.
What will I get if I cross bkue male to chocolate female, black and white female and lavender female?