You buy a 1 per 1. no 0.5 for cross class or anything shmuck. You gain skill points from level + ability + class(?), not sure.
You get a bonus for a specific skill from – race, or class or choosing a speciality from a field. Example – you choose concentration for your wizard’s special skill which grants you a bonus 2 to your skill.
skills are condenced into a schools of abilities you can make. Like Acrobatics (Tumble, Jump, etc.). When you choose a speciality you choose a scpecific performance you are good at. (+2 to that, +1 to the others)