1. This piece was made from very standard #10 crochet cotton, so matching material was easy to find.
These are all things you can do with cotton that is stitched at a fairly firm gauge. Not recommended for other fibers or very loosely stitched fabrics.
3. Crochet patterns are fairly easy to read, once you train your eye to see the stitches. Doilies are almost always repeats of patterns. This one is a combination of pineapples and Solomon's Knot stitches, with 11 repeats around. With so much of it intact, recreating the bits where the holes are was fairly simple.
4. This pattern is worked in the round, so here is the question: the damage is over a number of rounds of stitching. Is it better to take out all the rounds, or just restitch the bits where the holes are? Restitching the whole thing is a lot of work, but it can be done with a single strand of yarn, minimizing loose ends to tuck in. Restitching just where the holes are involves making short rows of stitches and tucking in the loose ends for each row.
The nice thing about thread-work is that the fabric is so visually complex that some tucked in loose ends here and there, especially in the small scale of thread (even #10), don't show up. So working short rows and tucking in the loose ends was the way to go.
This project went fairly quickly, once I had the time to sit down and focus on it. It came out fairly well, and its owner was pleased.