Hmmm. Some of this sounds all too familiar (as you would see if you checked out my thread, "Help, we can't keep him if he keeps attacking"...but that's another story!) I'm sorry to hear about Mr. Bean's eye...sure hope he doesn't develop any more problems with it.
I just thought I would add a bit about hissing and a few other things I have read and noticed about cat relationships. Hissing is generally not aggressive, it is defensive. If a cat is hissing, it is probably scared. It is very natural for the new cat (especially the smaller cat) in the household to be scared, and this may be how Lulu was showing her discomfort with her new environment. Cats also seem to have a pecking order, which may take a while to establish. There may be a disagreement between them about who gets to be "top cat". Both of our cats have sustained scratches and loss of hair in their process of working it out together. While hissing should not cause you too much worry, perhaps growling and screaming should. Our smaller cat will hiss at our big cat to ask him to back off when he chases or stalks her; growling and other more worrisome signs come only when he refuses to back off. When growling and screaming occur, both cats are given time away from each other, because it usually means that our little cat needs to be away from him because she feels seriously threatened.
As to your question about spaying...I think it may be time to have Lulu spayed -- some female cats come into heat as early as 5 months of age, and unspayed females are generally more high-strung than their spayed counterparts. You may find that she is happier all around and that relations between the two cats are improved once she no longer has hormones complicating everything. Who knows, some of what is going on may be sexual behavior.
I agree with Lotsocats' encouragement to wait out the first several tough weeks (or months), and not worry too much. Our cats are still working things out, after about 9 months together. Patience and willingness to try new things have been key for us!
Best of luck to all new kitty friends!