Basic website with login and vote member up/down

Early proof of concept needed to validate new idea. Initially functionality will take precedence over visuals. Future projects will refine and develop the proposal. Project stage 1 requires: Member account creation, secure login, retrieve password etc Admin accounts with additional priviledges Member details to include: name, email (unique), votes up, votes down, and additional customizable/optional fields Members can add themselves to 'Groups' by providing an identifier unique to that group Members and visitors can view each 'Group' to a page, with standard sorting and pagination options Members can click links to view full Member profiles Members can vote other Members up or down at most once per week (variable) Votes are stored and timestamped, they may expire or be cancelled Transfer of test site to our domain Project stage 2 may include: Facebook login integration 'Groups' have sub categories Identifiers for 'Groups' have verified/unverified state Forum integration Articles, content, links Tender is for Project Stage 1 while looking ahead to Stage 2. Any thoughts/suggestions about obstacles or additional functionality to consider at this stage is welcome.