For the main characters, no. Grassblades is about a homeless wanderer and the orphan who tags along with them; they literally HAVE no other clothes, and have to make do with washing/mending what they've got.
Some minor characters do get costume changes occasionally, though.
I do have some oneshot comics as well, but they don't have costume changes at all, since they take place over the span of maybe a few hours.
Sometimes, when there's a good reason for it! Like when I flash back to something that happened a long time ago, or if they show up in one scene, and then show up in another that canonically takes place days or weeks or more later.
Grassblades is set in a world where people in general have fewer sets of clothes to change between; it's a fantasy setting with no textile mills. So they change more rarely, and the variation tends to be smaller.
No, not really! I have a metric ton of reference photos saved that I can go dig through and find inspiration, so it's not that challenging. It's like with anything else you learn to draw; you have to find out what it looks like first. You wouldn't expect to be able to draw a bicycle without looking at a picture of one first - it's the same with fashionable clothing.
It's a matter of practise, really. Just keep trying until you learn how.
It's right up there ^ but if you don't wanna scroll up - here's a link to all of my series.
Not as such, no, but distinctive fashion and colour choices will make your character stand out, and help your readers remember them.