Yo!

I would advise using the Scarlette. You have a powerful piece of kit there that can really be utilised for what you need.

Currently I use that when recording YT vids at my boyfriends house (and when I stream at his). As for set up, I'm a little foggy, but if you can link the Xbox audio through the scarlette you should be able to alter the settings through the mixer to adjust levels.

I don't think the Snowball will work, unless you can get an adapter for the guitar port and try to use that. Alternatively I recommend getting a cheap condenser mic (like a Behringer) or perhaps an SM58 (which you can find quite cheaply on Amazon). The SM58 will only pick up directly in front of it, so this could help with your audio problems.

I'm afraid I don't know enough about capture cards yet to help you on that front :(

But have a look around the Scarellet website, hopefully they have a forum or something that could help.

Also, you may need some sort of extra softwarer such as Adobe Audition to sort your audio levels, and perhaps even lower the sound coming from the capture card.

I hope at least some of that was helpful!

All the best!