I definitely wouldn’t make her tank, her defense stat is too low for something like that. Plus, her special isn’t devastating enough to make up for it.
Personally, I think she should always be on the left- for her attack buff to get the maximum effect before any attacking/specials. She could manage in the wings, since she’s fast, or on the flank, since she does have quite a bit of health.
Depends on the setup to get more specific, but if I had to pick one: left flank if you’re counting on, and really need, her buff and cleanse, or left wing if she’s just there to help, but you’re not as dependent on her. Basically, if you already have a lot of great heroes: wing; if you don’t: flank.