To answer your questions:
Yes, you can alternate between co-washing and shampoo or low-poo (a shampoo without sulfates). Everything comes down to what makes your hair look and feel its best. Typically co-washing is done with a lighter conditioner (VO5 Kiwi Lime and Suave Daily Clarifying are both great co-wash conditioners). Focus on the scalp and make sure to use lots of agitation (rub your scalp really well). As long as you do this, your hair will still stay clean.
The conditioner that you just mentioned does have silicone in it, which would not make it good for co-washing (or for use as a conditioner when co-washing). Amodimethicone is a silicone that can only be removed by a sulfate shampoo or a shampoo that contains coco betaine. If you plan to continue to use shampoo somewhat regularly you won't have a problem with it, but if you move to primarily co-washing silicone products can cause problems.
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3a/f/iii Before the chop- Donated to Locks of Love, January 2013
Modified CG since 11/5/11
CO-WASH: VO5 Vanilla Mint Tea Clarifying, DevaCare No-Poo
CLARIFY: CHS Treatment Shampoo (used prior to PT/DT)
RO: DevaCare One Condition, Regis Olive Oil
LI: Cure Care, As I Am Leave-In
STYLE: Re:Coil, Curl Keeper, Biotera Gel, Deva Ultra Defining Gel, GVP Liquid Sculpting Gel, Curls Rock Amplifier and Strong Hold Mousse
PT/DT: IAGirl's PT, One n' Only Argan Hydrating Mask