I have both Chinese and Korean Epiphone Dots and Les Pauls.
The level of quality is pretty much the same.
As a matter of fact..... the new Epis coming out are better than ever!! I have a 2007 Trans Black Epi Les Paul Standard (made in China) that is extremely good!! It's a little nicer playing and more comfy than my others.
Also I think the stock Epiphone pickups are quite good, and an upgrade is not absolutely necessary.
Here are some clips i've done with stock Epiphone pickups:
YouTube - Epiphone Les Paul Trans Black
YouTube - Epiphone Dot part 4
YouTube - Epiphone Dot part 3
If you do upgrade the pickups eventually....... it will be the icing on the cake!