The character must be 9th level to create scrolls. The character can only create scrolls with spells that he knows. Up to 6 spells can be put onto one scroll. The costs and times listed are for every spell scribed.
Any components that are needed to cast the spell normally must also be expended to create the scroll-spell.
Potions are a bit harder than scrolls. The character must also be at least 9th level to create potions. Potions are basically based on spells, and that is how their level will be determined. The "spell" need not be known, but research must be done to get the correct formula for the potion. This research can only be done if you know the "spell", or if you have a sample of the potion. Also, the research requires a laboratory(mage) or a temple(priest). The research itself takes 2 weeks * level of the spell, and costs 100gp * level. If a sample is present, the time is halved, but the sample is used up. After the research is done, the potion can be made with these costs and times:
An exception is made for wilders. They may create potions without research facilities, but at a -25% if the potion is not based on a wild spell.
As with scrolls, any components that the spell uses must be used in the potion creation.
Other magical items are much more complicated then scrolls and potions. This includes protection scrolls. As such, their creation is decided entirely by the DM. No two items will have the same formula.