As you say brass bolts are oil / grease port covers,
under the right hand chain stay , there is a threaded post which goes through the bottom of the chain stay, no idea what the mounting is for, bolt just keeps the dirt out
Frame set
I have got this :
http://www.retrobike.co.uk/forum/viewtopic.php?t=168339
I have just finished painting it Light blue ( 2 pk epoxy )
with the head tube in silver
£150 plus P&P
Pm me if interested