Most demons have areas of expertise and areas where they are not willing to help, so you’re making quite a big request there which may not readily be fulfilled.
Two options are to ask the spirit you decide upon to create a familiar for you who will specialise in assisting that area, or, to read this post about a relative of mine who has now ascended to demonic form and who only had contact with the being he called Satan, his name is Varnaxis.
Either. 
Invoking usually means some kind of calling of the spirit’s consciousness or energy into yourself, evoking usually means calling them into a tangible (not necessarily VISIBLE) manifestation in your presence, separate from yourself, though there is some crossover and people also use the terms loosely, because magick is as much an art as a science.
There are methods to learn both, the book Evoking Eternity by E.A. Koetting will teach you almost everything you need to know to successafully evoke any spirit, and I’m not saying that as an ad, I think it will be a good first step for you. It’s available as a standalone e-book here:
Check out this seminar by E.A, regarding evocation:
King Paimon as you probably know likes music, and there’s no need to run a kind of “serial monogamy” with spirits, and cease working with one completely when you work with another, unless it’s for a specific reason.
This site deals with projecting out of your body and has good reviews on here: Free Lucid Dreaming Books and Guides. Download and Enjoy
The BALG course Mastering Soul Travel will expand your abilities, as well.