We're not having a cake, so don't need to worry about that, but I would assume that most kitchens/caterers would be able to provide a knife.
Toasting flutes - I never really understood this!
If we have toasts, we'll just raise whatever glass we happen to have in our hand at the time.
Pen - again, I'm happy to use anything, and most celebrants/churches will provide these.
But then, in case you hadn't already figured, I'm not that sentimental about keepsakes (they just clutter up cupboards for a few years until I get sick of storing them at which point they get chucked out!!)