Larger diaphragm headphones will provide better bass response, look for 40mm drivers or larger.
Closed-back over-the-ear headphones will prvide better sound isolation between the recorded sound and the 'live' acoustic sound so that you hear MORE of the recorded sound for monitoring. Also closed-back headphones will NOT BLEED sound as much that can be picked up by your mic if you have to drive the headphones at higher volumes.
Also, headphones that have a greater than 32 ohm impedance will be significantly QUIETER than those less than 32 ohm impedance. Most studio headphones are 50, 60 or 100 ohms, and you need to make sure that the output of the Focusrite interface can drive them with enough volume (voltage).
Keep in mind that using headphones for mixing and setting eq is a bad way to go since most consumer grade headphones SIGNIFICANTLY color the sound by over-compensating for lack of bass response, and if you set EQ levels in headphones and then play them back on actual speakers, the levels and EQ will sound really bad. It's best to have 'studio monitor' speakers for mixing tracks and finalizing.
Studio monitor speakers are designed to have a near-perfect FLAT frequency response that does NOT colorized the sound, OR to have a specific type of known sound coloration to test the mix for an intended target listening environment.
For uke, the studio monitors vs. headphones is not such a big issues, but if you are recording 2 or more instruments or 2 or more singers, simple laptop speakers are about the worst you can use. If you mix on them, and then make a stereo file and play that back in your car for example, you will find that the bass is muddy, the midrange is buried, and the treble is WAY too loud.
I'm over-simplifying here, based upon yrs of recording experience, but hopefully these will guide you into the right direction.
As far as mics go, I could write a book. If you already have some decent mics, then mic placement is going to be very important, as well as isolating background noise from your recordings. Any cardioid, hypercardioid or supercardioid mic will help here.
I would AVOID all omnidirectional mics, unless you want to record a group, sitting in a circle, with the mic placed in the center of that circle. omni mics, pickup everything in 360 degrees. Cardioid and it's variants, are designed to pick up most what they're directly pointed towards and reject sounds that are off axis from the front of the mic capsule...