Magic vs. Psionics
In Eberron, both magic and psionics are prominently featured and are expected to work directly side by side in a number of ways. Since Pathfinder does not have psionics natively, I will be using the psionic rules as presented by Dreamscarred Press, with the following clarifications. If your campaign world is not using psionics for whatever reason, please be advised that there are whole sections of this conversion that will not properly translate without those rules.
Magic / Psionic Transparency
Magic and psionics are both forms of the same raw energy, simply manifested in to different ways. However, their usage and understanding is very much alike, even more so in the Pathfinder rules set than in d20 v3.5.
Concerning Skills: Neither Psicraft nor Use Psionic Device are skills in the current rule set. Their usage has been merged into Spellcraft and Use Magic Device respectively, thus making Spellcraft and Use Magic Device equally useful for spells and psionics. The only skill that remains separate is Knowledge (psionics) as there is enough of a difference between magic and psionics to not have it combined into Knowledge (arcana), thus whether or not it is counted as a class skill is determined separately from Knowledge (arcana).
Concerning Usage: Both spells and powers have a number of similar attributes and, except where detailed otherwise, most are considered equivalent.
The two areas where spells and powers differ the most is concerning how they are stored and spent and components used. As psionic powers are manifested without the need of verbal or somatic components, effects that limit or affect these requirements do not apply to psionic powers.
Spell Slots vs. Power Points
Although in direct application, psionic powers and magical spells are nearly identical, there is one application that often causing some significant confusion: the spell slot vs. power point conversion. Where spells have specific spell levels and a certain number of slots for each spell level, all psionic powers are spent from the same pool, with the power level of each power determining the power point cost from this pool. While there are 0th level spells, there are no 0th level powers (although there are certain powers, based on one's discipline, that can be manifested for free without augmentation, taking the place of 0th level powers), and since spell levels and power levels are equivalent, you can use the below table to determine the power point cost of a specific spell level. Thus, 1 Power Point has the same impact and effect as a 1st-level spell. For larger quantities, divide the Power Point cost by 2, rounding up, to get the equivalent spell level. This works both in direct power level to spell level comparisons as well as alterations to power and spell levels from feats and other effects.
While this process works well for translating from psionic powers to spells, the reverse is not as clear. Occasionally, there will be powers or spells that directly affect future uses of spells or powers, either as limitations or benefits. In these situations, use the following precedents.
Efficiency Reduction: Certain powers, like Catapsi, cause future use of powers to cost more power points, effectively making the power less efficient. However, since spell slots are not divided up in the same manner, this is how to apply such powers to spellcasters.
Determine Spell Level Equivalent: When an effect causes powers to cost more power points, determine what the difference in spell level is by dividing the power point cost different in half, rounding down. For example, Catapsi lists a difference of 4 power points to all powers that fail a Will save. Thus, any spell cast would have a difference of 2 spell levels for those that fail a Will save.
Limitation on Higher Level Effects: If the Spell Level Equivalent is 1 or more and the original effect is still limited by the Manifester Level limitation on psionic manifesters, then while under this effect, spellcasters cannot cast spells from a number of their highest spell levels equal to the Spell Level Equivalent. Thus, an 17th wizard affected by a Catapsi effect cannot cast 9th or 8th level spells, since the spell level equivalent for Catapsi is 2. Should he encounter an effect that had a Spell Level Equivalent of 4 and was limited by Manifester Level, then he would not be able to cast spells from 6th, 7th, 8th or 9th level spell slots while affected.
Sacrificing Spell Slots: If the Spell Level Equivalent is 1 or more and the original effect causes an increase in power point cost, then an affected spellcaster would need to sacrifice a number of spell levels equal to the Spell Level Equivalent. These sacrificed spell slots do not need to be of the same level and any combination of sacrificed spell slots that covers the cost of the Spell Level Equivalent is permitted. However, if the spellcaster needs to sacrifice a spell slot that is higher that the Spell Level Equivalent, any remaining spell levels left over are still available to the spellcaster, but can only be used to either replace lower level spell slots that were already sacrificed in this manner or as a bank to draw from for future sacrifices needed. This choice is made at the same time that this higher spell level slot is sacrificed. These 'phantom' spell slots are all purged from the spellcaster at the next time he rests to regain his spell slots.
Memorization Spellcasters: When sacrificing spell slots, memorization casters do need to determine which memorized spells are being sacrificed in this manner and which memorized spells, if any, are being restored when a higher spell level slot is being sacrificed.
Magical Items: Items that provide additional power points cannot be used to provide additional spell slots or vice-versa. Likewise, magical items that provide additional spell slots cannot be used as sacrificed spell slots. This specifically includes Pearls of Power and Runestones.
Spell-like vs. Psi-like Abilities: As these are almost exactly the same, any alteration to one effects the other in the same way.
Magic vs. Psionic Item Creation
As the feats needed to create psionic items are now no longer separate feats, those that have these feats can create either type. However, there is a special exception of the caster level vs. manifester level equivalent. With the exception of the artificer class, classes that provide a caster level do not count toward manifester level and vice-versa.