I have a MPK249 keyboard, FL Studio for the beats, and a Scarlett for my interface and I'm need someone who is technical enough to help me out with a couple of problems I'm having

EDIT: [My Set-Up and Problem]

I have my FL Studio opened up, connected to my computer (Windows 10) is my Akai MPK249, and my Scarlett 4i4 connected to my PC as my interface. Connected to my Scarlett's Front is my Headphones.

Scarlet 4i4/Back Side: Input 3-4, Output 1-2, and Output 3-4.

I have two 1/4" TSR connected to Output 3-4 going into Input (L/R) of my Boss RC-505mkII.

I then have two 1/4" TSR connected to the Output (1/2) of my Boss RC-505mkII going into my Scarlett's Input 3-4.

Problems:

1. I use my Midi Keyboard to make a beat, and the Boss RC-505 records it, how ever it also picks up all of window's (The Computer) noise. How do I make it only listen to the sounds from FL Studio while I can also hear the sounds from FL Studio and the Boss RC-505?

2. When the I record the second loop, it hears the first loop, which then causes a feedback loop which may be due to problem 1. How do I prevent this?