You will need

Sweater
0-3mths (16in Chest) - 1 Ball
3-6mths (18in Chest) - 1 Ball
6-12mth (20in Chest) - 2 Balls
12-18mth (22in Chest) - 2 Balls

Tank Top
0-3mths (16in Chest) - 1 Ball
3-6mths (18in Chest) - 1 Ball
6-12mth (20in Chest) - 1 Ball
12-18mth (22in Chest) - 1 Ball

2.75mm and 3.25mm Knitting Needles
Stitch Holders