Wood plane? and Stock blades

Hi there. There is actually a similar post asking about sanding, but i didn't want to hi-jack the person's post with a new question but I had a similar problem building the pottery barn bed. (ok also some pieces weren't square but that's my fault for not checking)

I have a a piece of wood (the bottom shelf) that was cut really weird. I think the blade should have been replaced on the cir saw i was using. The cut kind of rounded itself (or i had the saw at a weird angle somehow) and when i put it together it was about 1/4" too wide so it sticks out slightly. I was originally going to try to mask it some wood filler but that didn't work. I've previously tried to correct a cut that was about 1/4" off before and that was a scary horrible disaster and I am never doing that again. Would a wood plane be a good option? I know that is too much and too long to sand down unless i have a power sander (and i don't). I've looked up wood planes before with their tiny tiny strips being taken off at a time. I thought that may not have been a good choice and am now rethinking this decision.

Also, the circular saw noted above was a loaner from a friend and now that i am not afraid of it I got my own saw for my birthday last month and am about to start my first project with it on 3/4" BC plywood. Should i use the stock blade or just go ahead and switch it out for a new one? I was thinking it might be ok but then i remember when you buy a new printer it comes with a "starter cartridge."

Thanks in advance anyone who helps me out with this. I never knew i would have enjoyed building things until i stumbled upon this site.