Here is my stab at this. -This might be long-
My ways of dealing the issues you presented here (Issue 2 and Issue 3) would be to find other activities you like. Here's an example for ya, I usually like to go for walks around new or familiar places, (in my case) such as heading to downtown Houston or riding a train/Metro Bus. The scenery, Leisure activities, and other things helps take in idea's, but these unfiltered ideas can fly away pretty quickly. The key is to retain the ideas that fly in your mind, quickly.
I do this by jotting down my unfiltered thoughts in my head on my notepad in my phone. Don't worry if they (the ideas) sound silly, you can chose through them later. The important thing is to have a list of Ideas in front of you, so you can chose (and refine your chosen ideas). (This is how i create my scenarios, Ideas and artwork b.t.w)
Summary - Thinking too hard about it (Your creatives, Art, Writing,) MIGHT actually make you not think anything of substance.
To further clarify this, You don't have to do what I displayed here (The specific leisure activities), the point is to engage in something else
WITHOUT focusing too much on your drawing and Writing. After doing that,
Ironically, the ideas in which you can USE for your writing and art,
will flow into you.
I really wish i could help with (Issue 1) But i don't play any instrument.
Oh and about drawing skill... Don't mind that too much, just worry about dealing with blocks for now.
Good luck, let your creative spirit roam free!