#Yes

The rules require you to meet the prerequisites by having an ability score of X or higher. Assuming your items allow you to reach that target number, then you can take a level in that class. This is not stated explicitly, but there are no other situations (that I can find) in which you use your natural ability score instead of your enhanced one while benefiting from a magical item. Thematically this makes sense. If you outfit yourself in gear that increases your intelligence, it will become easier to study, memorize spell formulas, and do other intelligence based tasks.

##What happens if you lose that item?

In previous versions of the game when your ability score is lowered to below a prerequisite of an ability, most often feats, you cannot use that ability. This is not a direct correlation, but it does offer some insight into historical intent. My gut reaction is that if for some reason you lose the effects of your magical items you will be unable to use class abilities and features until the ability score is restored. This would be entirely up to your group and your DM though, as this is outside of any RAW that I can find.

Yes

The rules require you to meet the prerequisites by having an ability score of X or higher. Assuming your items allow you to reach that target number, then you can take a level in that class. This is not stated explicitly, but there are no other situations (that I can find) in which you use your natural ability score instead of your enhanced one while benefiting from a magical item. Thematically this makes sense. If you outfit yourself in gear that increases your intelligence, it will become easier to study, memorize spell formulas, and do other intelligence based tasks.

What happens if you lose that item?

In previous versions of the game when your ability score is lowered to below a prerequisite of an ability, most often feats, you cannot use that ability. This is not a direct correlation, but it does offer some insight into historical intent. My gut reaction is that if for some reason you lose the effects of your magical items you will be unable to use class abilities and features until the ability score is restored. This would be entirely up to your group and your DM though, as this is outside of any RAW that I can find.

Yes

The rules require you to meet the prerequisites by having an ability score of X or higher. Assuming your items allow you to reach that target number, then you can take a level in that class. This is not stated explicitly, but there are no other situations (that I can find) in which you use your natural ability score instead of your enhanced one while benefiting from a magical item. Thematically this makes sense. If you outfit yourself in gear that increases your intelligence, it will become easier to study, memorize spell formulas, and do other intelligence based tasks.

What happens if you lose that item?

In previous versions of the game when your ability score is lowered to below a prerequisite of an ability, most often feats, you cannot use that ability. This is not a direct correlation, but it does offer some insight into historical intent. My gut reaction is that if for some reason you lose the effects of your magical items you will be unable to use class abilities and features until the ability score is restored. This would be entirely up to your group and your DM though, as this is outside of any RAW that I can find.

#Yes

The rules require you to meet the prerequisites by having an ability score of X or higher. Assuming your items allow you to reach that target number, then you can take a level in that class. This is not stated explicitly, but there are no other situations (that I can find) in which you use your natural ability score instead of your enhanced one while benefiting from a magical item. Thematically this makes sense. If you outfit yourself in gear that increases your intelligence, it will become easier to study, memorize spell formulas, and do other intelligence based tasks.

##What happens if you lose that item?

In previous versions of the game when your ability score is lowered to below a prerequisite of an ability, most often feats, you cannot use that ability. This is not a direct correlation, but it does offer some insight into historical intent. My gut reaction is that if for some reason you lose the effects of your magical items you will be unable to use class abilities and features until the ability score is restored. This would be entirely up to your group and your DM though, as this is outside of any RAW that I can find.