Did you try it on a different camera?

Had a similar issue with one of my lenses and in the end it turned out my camera was having an issue with the connecting to the lens. Putting the lens on a different body to modify the setting there and using a differentialen on my camera cleared the issue.

Take the input and improve your work.

Maybe a professional portfolio review by another photographer will help you to identify areas to work on.

What to do with raw photos:

• transfer everything from the camera and card to a NAS
• import everything into Lightroom or similar management software
• go through the photos and mark bad shots
• delete them
• go through the photos and mark unusable shots
• delete them
• go through the photos and mark the ones you want to edit
• go through the photos that are not marked for editing and select lesser duplicates
• probably delete them

Edit the ones you marked and keep the remaining in case you need them later.

The cheapest place is at home.

https://www.lab-box.it/

There are a ton of photography subreddits on Reddit I‘ve heard.

If you are going for business customers you will need more than just good photos.

These customers have specific needs tied to their business goals. If you can pitch concepts that address these needs you have a chance to get hired. If you just show up with a nice portfolio you have only wasted everyone’s time.

Prepare before meeting those clients and do some research for the pitch.

You could rent one.

Scout the location for good viewpoints and angles (same time as the parade).

Probably a good idea to carry two cameras with different lenses.