Joomla migration from 1.5 to 2.5 and other functionalities

Project Description: I need to upgrade the website to Joomla 2.5, change template and configure/add some new functionalities. Before upgrading I would like to a) check all installed components and plugins and confirm availability for Joomla 2.5. b) Propose upgrading/changing component to better ones (free or paid) The upgrade has to happen without disruption to existing website (please provide references to previous upgrades and an idea of the plane - for example use of jupgrade). After the upgrade I would like to move to a new template: the favorite option is Yootheme Revista with Zoo and Widgekit. New Functionalities ============== >SOME KIND OF PAYWALL Registered User: Registered users can sign up for newsletters and read up to 5 (it can be changed) premium articles per month + other website functionalities to be developed (for example being able to query a database of companies, access some special content, etc.). Registration is a multi-step process that collects demographic information (managed via RS-Form?). Subscriber: unlimited access to the website + other website functionalities to be developed (for example being able to query a database of companies, access some special content, etc.). It also receives print magazine and in the future a digital magazine swiflet. VERY IMPORTANT: As a Registered or Full Access user you should NOT have to login every time you connect to the website (Facebook style). >PREMIUM ARTICLE Article in blog layout can be tagged as premium. To access Premium articles you need to subscribe to the magazine. ----------- >BANNER SIZES: Banner size has to follow IAB Universal Ad Package Guidelines ([login to view URL]) ----------- >SUBSCRIBE TO THE MAGAZINE This is a Paypal supported subscribe process (multi-step to collect demographic information). It can be done via RS-Form. ------ >STOCK TICKER ----------- >CLASSIFIEDS / JOB POSTINGS A self service tool to post job postings....initially free but ready to become a paid option ---- POP UP REMINDER A pop up window after clicking few links on the website to remind to register/subscribe to get all the benefits. This should not happen for registered user/subscribers (see above) ----------- MOBILE CAPABILITIES ? If you have any knowledge on mobile accessibility that would be nice. ----------- We would like to minimize references to Joomla....we noticed that the server gets a lot of attempts to get information currently. ------ We would like any change done to be documented for future reference.