Paths of online users towards a purchase event (conversion) can be very complex, and guiding them through their journey is an integral part of online advertising. Studies in marketing indicate that a conversion event is typically preceded by one or more purchase funnel stages, viz., unaware, aware, interest, consideration, and intent. Intuitively, some online activities, including web searches, site visits and ad interactions, can serve as markers for the user's funnel stage. Identifying such markers can potentially refine conversion prediction, guide the design of ad creatives (text and images), and lead to higher ad effectiveness. We explore this hypothesis through a set of experiments designed for two tasks: (i) conversion prediction given a user's activity trail, and (ii) funnel stage specific targeting and creatives. To address challenges in the two tasks, we propose an attention based recurrent neural network (RNN) which ingests a user activity trail, and predicts the user's conversion probability along with attention weights for each activity (analogous to its position in the funnel). Specifically, we propose novel attention mechanisms, which maintain a global weight for each activity across all user trails, and also indicate the activity's funnel stage. Use of the proposed attention mechanisms for the first task of conversion prediction shows significant AUC lifts of 0.9\% on a public dataset (RecSys 2015 challenge), and up to 3.6\% on three proprietary datasets from a major advertising platform (Yahoo Gemini). To address the second task, the activity weights from the proposed mechanisms are used to automatically assign users to funnel stages via a scalable scoring method. Offline evaluation shows that such activity weights are more aligned with editorially tagged activity-funnel stages compared to weights from existing attention mechanisms and simpler conversion models like logistic regression. In addition, results of online ad campaigns in Yahoo Gemini with funnel specific user targeting and ad creatives show strong performance lifts further validating the connection across online activities, purchase funnel stages, stage-specific custom creatives, and conversions.