what size fasteners?
 

I got an aluminum frame Raleigh SC30 with nearly all part present, except the fasteners.

What size screw do i use for the front derailleur bracket?

There are 2 holes at the bottom of the bottom bracket, one is threaded. Which hole do i use for the plastic cable guide and what type/thread fastener do I use?

Once I can get these secured, then i should be able to at least ride.

Just about all front derailleurs use 5x.8mm screws, both for the clamp or to mount to a braze on.

Likewise for most BB cable guides which mount with the same 5x.8mm hardware, but here there might be more variation.

I don't know what the second hole in the BB shell is. It could be intended as a weep hole to drain water, an aid to make threading internal wires easier, accept a pin so the plastic guide doesn't move on the single mounting screw, or simply to save weight. A good look at the frame, and some thought should give you the answer, and if you can't figure it out, but the plastic guide fits, then don't worry about it.

I hope you have the FD braze-on (bracket). The screw will come with the FD.
Use the threaded hole in the BB for the cable guide. You use the same thread screws as used for the water bottle braze-ons, but it'll need to be shorter. (4mm * ? pitch). Hex cap cap screws are always good.

That is most probably it's function. All of my frames have that second unthreaded hole and it's obviously there to allow tramp water to escape.