Thanks for all the advice so far! Is it okay to do military press with an Ez curl bar if you don't have enough room to do it with a regular straight barbell?

I would suggest you do it with dumbbells instead. An E-Z Bar could work but it might feel a little funky gripping it for an overhead press. If you can do it comfortably go for it, otherwise hit them dumbbells! 🏋 

Are leg lunges a compound movement? Do they work the same parts of your legs as squats do?

Yes lunges work your glutes, quads and hamstrings too - depending on how far you lunge will change how much activation you get in different areas. A shorter lunge will have more quad activation, and a longer lunge will have more glute activation.

What are some good warm up exercises for your legs before a leg workout?

I would do some bodyweight squats or squats with just the barbell to start with - maybe 2-3 sets, then maybe 2-3 more sets before you start your working sets. You can also do things like bodyweight lunges, maybe 5 minutes on a bike if you like, some low rep box jumps for explosiveness (3-5 reps per set). Things like that work great! Also try these stretches below to open up your hips.

What are some good beginner exercises you can do for your core?

Well the basics are a good start - crunches, planks, V-Ups. Have you searched through the site or even my channel for ab workouts? There are plenty out there!

Is it better to eat before or after a workout for muscle gains?

Your post-workout meal is more important than a pre-workout meal. Pre-workout is more of a personal choice - post-workout is more important because that's basically the start of your recovery and the rebuilding process for your muscles to become bigger and stronger.

A good meal with a decent amount of protein and carbs and some fat is ideal post-workout, and it's usually a good idea to get a protein shake in as well if it's going to be a while until you actually have that decent meal. Some fast acting/sugary carbs are good too, so that can come from fruit or a little bit of something sweet.

Is it better to eat before or after a workout to see muscle gain?

What are some good protein supplements, bars or shakes you can consume as a beginner?

Real food is the best protein source for you my friend 😁 Focus on getting as much protein as you can from wholesome, nutritious food first and foremost, then if you have some gaps that need filling, you can look to a protein supplement (powders would be your best bet over bars, both in terms of cost and ingredients).

Some protein options off the top of my head are chicken, beef, fish, tofu, beans, quinoa, eggs, Greek Yoghurt, dairy etc. Check out this list for more ideas! http://muscularstrength.com/article/healthy-shopping-list-for-life

If I couldn't do squats with a barbell on my back, then would it be okay to just hold on to a weight or hold some dumbells up by my shoulders?

Sure you can do squats with dumbbelsl on your shoulders, it will be difficult to balance them when starting to go heavy though.. it can be dangerous.

I'd suggest you look at why you can't do squats with a barbell on your back too - is it because of some kind of injury? Or do you just need better shoulder mobility? Can you do front squats?

I have no injuries. I was just wondering. I don't have enough room to do squats with a regular straight barbell, so my only option would be to use an Ez- curl bar. Would this work? I've never done front squats. What's the difference between those and regular squats?