I, too, am a hand quilter. With the age of this flimsy, I'd be consistent with the age of the fabrics and hand quilt it, using either a cotton or a poly batt. I sometimes do not use quilting thread but the same thread that I sew with. I have had no problem using it, either while quilting or as the quilt is used.
There must have been a time that yellow was popular. I just came across blocks that my mother put together and there is that same yellow that you have in the pictures. It wouldn't have been my choice but it must have looked good to her! She put a lot of time into these blocks so I will leave the yellow and get the blocks together. It appears like Jack's Chain but the 1/2 blocks for between the blocks aren't there. She left "a million" little 9 patch blocks that I could continue on unless I decide to put these together another way. I can see pencil marks that each of the squares of the 9 patch were individually cut--no rotary cutting or strip piecing there!--and all are consistent size. Seams are more like 1/8" than 1/4. As I remember her machine, that it about the width of the presser foot on that machine though. This is going to be a challenge but, as with you finishing your own mother's work, it will be rewarding. We will hope our moms are watching.