Fumes from super glue will corrode the photodiode. Silicone seems to be fine. I'm assuming the acrylic cement has the same stuff as super glue.
I don't think so. Super glue is cyano acryliate. It like something like weld-on is dicholromethane. They work on two different principles - super glue adds a plastic-ish compound between the surfaces that grips both surfaces. Acrylic cement melts the acrylic, causing the two surfaces to re-crystallize as a single structure.