So sorry to hear of the damage to your wonderful old tree.* You don't say if this is a fruit bearing tree or an ornamental.* You can plant the seeds from the fruit but you won't get the identical fruit as you won't know which tree crosspollinated with it.* Either way you can take cuttings, which is what I would suggest so you get the same tree.* Is yours a fruit bearing tree or an ornamental?* Do you know the particular variety?* This will help with which method of propagation to use.
Pear trees are notorious for having brittle limbs and poor crotches so good pruning practices while it's young are important to help it form a strong structure.* Once we know which type you have I will give you some sites on how to prune your new tree.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.