Need advice on preventing dye bleeding and using satin binding for my first ever blanket! Sewing Machines Parts and Sales in Los Angeles

First of all I know this is a really long post so I’m going to put all my questions in bold for readability.

OK! So I would like to think that I have a decent idea of what I’m doing but I really don’t want to fuck this up and there are a lot of parts I haven’t done before so I thought I’d ask for some help first.
(Experience: one semester of working in the costume shop @ my college and one semester of wardrobe crew, along with some minor mending projects and a lot of cross stitching which never made it to a finished piece. The most complicated piece I’ve made by myself was this toddler backpack)

ANYWAY, my project is going to be a weighted blanket! My boyfriend’s brother is 18 years old and nonverbal/severely cognitively delayed because of a missing chromosome of some kind, and his parents have trouble getting him to calm down at night or if he gets upset when they’re out, so I thought they might like one for christmas instead of paying $150 online (srsly, stores?)

I am going to be following this weighted blanket tutorial as a basic guide. Since the filling is relatively expensive, I am going to be making a 6 lb. lap blanket, roughly 1.5 x 3 feet. I’m basing the weight/size off of this product.

My first issue is with the fabric. He really loves disney princesses (his mom likes to imagine that he thinks they’re his girlfriends which is adorable) so I got the last yard and a half of this fabric at Joann’s last night. I forgot to check while I was there but I’m almost positive that it’s 100% cotton. Just from how saturated it is, I am kind of worried that it might bleed later. They’re going to need to wash it often since he is rather messy.

I’ve done some research and I’m not sure how to deal with this. One person told me to wash it in citric acid, but they didn’t have any at the craft store close to me. Some internet people say that they don’t wash it beforehand because it’s easier to cut out pieces and washing makes the edges fray. I asked the fabric department at my craft store and they said that I could wash it in vinegar? And finally I know my Grandma usually soaks colorful things in a sink full of cold water for a few hours.

I definitely want to wash it beforehand so that it doesn’t shrink after I’ve put it together so my first question is what is the best way to wash the fabric now so that the colors don’t bleed into each other and the edges don’t fray in the wash, preferably without having to order any special fabric treatment online? (I’m near a Hobby Lobby so I can run out to get common things but I need this to be done by christmas so I can’t wait for online orders to ship)

OK next issue: Before this, I’ve really only sewn pattern pieces together. For this project, I am going to have to cut two large rectangles of fabric with straight perpendicular edges, and I am not sure how to do that. I have a fabric marking pencil, a large kitchen table, a yardstick and several rulers, one of those triangle thingies that you use to mark corners, and some fabric scissors. I would assume that I can use all these things to turn my fabric into nice neat rectangles but I’m unclear on the specifics.

When I’ve used the corner thingie on paper and cardboard, I’ve sometimes managed to have all four corners be nice right angles but somehow not quite lined up with eachother. I’d imagine this problem would be magnified when you’re working with fabric, since the weave isn’t as fixed as paper is. IDK what the right words are but like how when you cut a square of it you can pull on the corners and it’ll be more like a rhombus and then anything you mark on it will be warped when you straighten it out again? That would be bad. So my question is how can I cut nice straight even rectangles without having to buy more tools?

My last two issues have to do with finishing the edges. The tutorial I mentioned earlier isn’t super specific, and I wanted to bind the edges since I don’t have a serger. So, I found another tutorial for a plain ol’ non-weighted baby blanket which I’m going to follow once I have all the pellets sewn in.

First question on this part should be pretty simple. The author does a zig-zag stitch to secure the edges of the blanket before they sew the binding on. I’ve never used a zigzag stitch on an edge before and I can’t tell how they’ve lined it up. It looks like one side of the “points” are just slightly off the edge of the fabric, but wouldn’t that make it come apart, if they’re not anchored in anything? I would think that at the least you’d have some loose little loops of thread hanging off the edge. Is that really how it’s supposed to be done or am I looking at the picture wrong?

Finally we’re at the very last question of this post! If you’ve made it this far, you are definitely my hero and an awesome person! After I’ve zigzagged the edges, I’m supposed to put the binding on. I got this stuff from Hobby Lobby just now. I’m a little confused by the fact that the edges just sort of… end. Like they’re not folded over or anything. Is that OK? I thought that having edges exposed was a Bad Idea because they’ll fray and stuff. Am I supposed to fold them in myself? Is the binding made of something that won’t fray even though the edge is right there?

tl;dr (but please read the whole post?)

• How do I keep my fabric from bleeding?
• What’s the best way to cut large, straight, even rectangles without a whole lot of tools?
• I’m confused about whether the edge of a zigzag stitch is supposed to be over the edge of my fabric
• I am not sure if I am supposed to do something with my blanket binding so that the edges are tucked away, or if it’s fine to just leave them in the open