I have some UPVC window frames (Bay window), and the previous owner has
put nice roman blinds on them. I want to keep the blinds, but the sticky
pad that the strings tie too keeps coming off.
Can I *safely* drill 2 small holes and install a hook held on more
firmly with two screws ? do i need special screws, or is there an
alternative option?

Also, I have a metal front door (at least, that's what it feels like)
and frame. I want to fit a door chain - again, that needs drilling, and
I've never drilled into metal... any special screws/considerations I
should consider ?

Ian