Is this bspp or bspt?

This G Thread is Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread. No Washer Needed.

will this work for attaching a shower head U.S. standard thread to metric shower assembly? Thanks

Yes

Is this material safe for drinking water?

Yes it is safe for drinking water. It is LEAD Free.

Where can I get a 3/4" bps (British) male to ght (American garden hose thread) female adaptor?

You will probably need to use 2 fittings, 1 to convert to standard NPT and then another to hose. Honestly though you can probably thread your garden hose right onto the BPS without worry.

Will this allow me to connect a female G1/2 hose to a normal sink aerator?

Yes, you can use this adapter to connect a female G 1/2 hose to a 1/2" NPT sink aerator.

I am looking for the r ( bspt) version of this adaptor

if You need the reverse of the above adapter, then please check the other listing here: https://cascadashowers.com/collections/fittings/products/g-thread-metric-bsp-3-4-female-to-npt-thread-3-4-male-pipe-fitting-adapter-lead-free-3-4-inch-1

Where can I get a 3/4" bps (British) male to ght (American garden hose thread) female adaptor?

Thanks for your question. We don't sell ght (American garden hose) thread adapters.

How much additional length will this adapter add if screwed into 1/2" npt female supply line? I need to extend about 5/8" for new wall tiling project.

This adapter will add 5/8" .

looking for a fitting 14.7 mm female to 1/2 inch male about 1 1/4 long

We are out of stock of this Adpater size.

Will this work for a natural gas line connection to BBQ whip?

No the threads don’t match.