Questions about Magento API

Hello, I am in need of an expert in Magento v1 API, SOAP v2 or v1. What I am trying to accomplish is the following: I am trying to write a mobile app for a friend and I have some troubles with integration with SOAP and I have 2 main questions for you basically. Please bid only if you have worked with Magento SOAP. This is a 10 minutes job. 1) How do I get for example the images of a category, I have the call for SOAP catalogCategoryTree but I don't get any images associated, how can I get the images, please provide an explanation and a snippet. 2) Normally I do a login with app user id + token to get a session to do all subsequent calls. What about login-in with an actual customer and seeing his profile? Also doing a checkout on an actual customer (not anonymous). I see the calls require a sessionID as well, but don't know how to login with a customer to get that sessionID to pass for example to customerCustomerInfo call. So a small snippet or indication on the direction to go, because login only takes user id + token and not username+password is what I will need. Again, please bid only if you have worked with this before so that we don't waste both of us time. Thank you.