Sorry if this has been asked before. I searched and couldn't find a comparable post (maybe I'm dumb but anyway...)

I haven't been going to the gym as often as I'd like. On some days I think it would be easiest for me to go to the gym right before my work day. My work clothes are pretty basic (no suit or anything) but I still want them to be clean and not too wrinkled. The small neighborhood gym I go to has 3 single-use bathrooms, each has a basic shower inside. There is a set of small cubbies nearby to keep your stuff in during your workout. I have 3 questions:

a) My job is physically active. I'm tired and my feet hurt after a normal shift without working out. Any tips on how to get through it all with a workout added beforehand?

b) What extra stuff should I bring with me? Obviously toiletries, but anything else you find helpful?

c) Is there a good way to protect my work clothes from getting all fucked up in my gym bag?

Bonus: Any recs on commuter organization and/or specialized bags?