Sure, happy too, be advised that it’s just my layman advice based on my own experiences.
I’d suggest an audio interface with 2 headphone jacks, as pretty important. You’ll inevitably want to listen louder at some point and it’s nice when you and the person you’re jamming with can both throw on headphones and hear the same mix. I have a Mackie Motu Track 16.
I’d suggest a longish desk, so you have space to spread things out. Countertops and kitchen cabinets work really well for this, and Ikea makes some table tops you can pick up for cheap.
Laptop stands make great drum machine stands.
Hmm, what else. Speaker placement is something I just do my best with. Whenever I move my stuff around, I do a quick internet search to try to get them as close to however they are supposed to be according to whatever picture my internet search returned.
Inevitably though, you and your playing partner end up positioned outside of the stereo field though, but when stereo separation becomes important you can just throw on your headphones.
Like, really the main goal should be comfort and immediacy. Switch things on and get to making sound with minimal fuss. That’s the strategy I shoot for anyway.
Not much concrete for you to go on there, but maybe you’ll find it helpful and some other folks will chime in. 
edit – - - Drats - I didn’t realize this was the tiny studio corner thread when I posted. A super long table won’t work for a tiny corner, lol. 
